Novel naphthylenyl compounds for long-acting injectable compositions and related methods

ABSTRACT

The present invention provides compounds useful for the treatment of opioid dependence, alcohol dependence, alcohol use disorder, or the prevention of relapse to opioid dependence in a subject in need thereof. Related pharmaceutical compositions and methods are also provided herein.

RELATED APPLICATIONS

This application claims of benefit of U.S. provisional patent application Ser. No. 62/697,890, filed on Jul. 13, 2018, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to novel naphthylene-containing compounds and their use in long-acting injectable compositions. In particular, dimeric prodrugs of naltrexone are disclosed herein. The invention also relates to methods of use thereof.

BACKGROUND OF THE INVENTION

Opioid dependence and alcohol dependence are chronic disorders that result from a variety of genetic, psychological and environmental factors. Traditional treatment has consisted of two phases: detoxification and rehabilitation. Detoxification ameliorates the symptoms and signs of withdrawal while rehabilitation helps the patient avoid future problems with opioids or alcohol. In the past, many rehabilitative treatments have been psychosocial. More recently, there has been increasing interest in medication-assisted treatment. The successful treatment of opioid dependence or alcohol dependence has many serious challenges and complications. Patient compliance can be a particularly difficult challenge to overcome. Accordingly, there is a need for novel and improved therapies.

SUMMARY OF THE INVENTION

The compounds and methods described herein comprise one or more prodrugs of naltrexone. Upon administration, the compounds of the invention can be converted in vivo to naltrexone. Following conversion, the active moiety (i.e., naltrexone) is effective in treating subjects suffering from opioid dependence or alcohol dependence or at risk of developing opioid dependence or alcohol dependence.

The invention provides prodrugs of naltrexone (NTX) having one or two molecules of naltrexone covalently bound to a naphthalene-containing moiety. The compounds of the invention may extend the period during which the naltrexone is released and absorbed after administration to the subject, providing a longer duration of release than other commercially available naltrexone products, such as VIVITROL® (naltrexone for extended-release injectable suspension) or REVIA® (naltrexone hydrochloride tablets USP).

Provided herein are compounds useful for the prevention or treatment of opioid dependence or alcohol dependence in a subject in need thereof.

In an aspect, provided herein is a compound of Formula I:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4;

wherein the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound with points of attachment selected from the 1 and 1′ positions, the 1 and 4′ positions, the 2 and 2′ positions, or the 2 and 3′ positions; and

further wherein the R groups are bound with points of attachment as follows:

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 1 and 1′ positions, then the R groups are bound at the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions;

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 1 and 4′ positions, then the R groups are bound at the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions;

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 2 and 2′ positions, then the R groups are bound at the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions; or

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 2 and 3′ positions, then the R groups are bound at the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

Examples of a compound of Formula I provided herein include a compound of Formula Ia, Ib, Ic, or Id, or a pharmaceutically acceptable salt thereof.

In another aspect, provided herein is a compound of Formula II:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4;

wherein the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound with points of attachment selected from the 1 and 1′ positions, the 1 and 4′ positions, the 2 and 2′ positions, or the 2 and 3′ positions; and

further wherein the R groups are bound with points of attachment as follows:

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 1 and 1′ positions, then the R groups are bound at the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions;

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 1 and 4′ positions, then the R groups are bound at the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions;

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 2 and 2′ positions, then the R groups are bound at the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions; or

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 2 and 3′ positions, then the R groups are bound at the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

Examples of a compound of Formula II provided herein include a compound of Formula IIa, IIb, IIc, or IId, or a pharmaceutically acceptable salt thereof.

Also provided herein is a pharmaceutical composition comprising a compound of Formula I or II, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

Also provided herein is a method of treating opioid dependence in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof. In an embodiment, the opioid is an opioid agonist. In an embodiment, the opioid is morphine, fentanyl, oxymorphone, buprenorphine, hydromorphone, oxycodone, hydrocodone, diamorphine (i.e., heroin) or the like. In another embodiment, the opioid is oxycodone or diamorphine. In another embodiment, the opioid is buprenorphine.

Also provided herein is a method of treating alcohol dependence in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof.

Also provided herein is a method of preventing opioid dependence in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof. In an embodiment, the opioid is an opioid agonist. In an embodiment, the opioid is morphine, fentanyl, oxymorphone, buprenorphine, hydromorphone, oxycodone, hydrocodone, diamorphine (i.e., heroin) or the like. In another embodiment, the opioid is oxycodone or diamorphine. In another embodiment, the opioid is buprenorphine.

Also provided herein is a method of preventing relapse to opioid dependence in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof. In an embodiment, the opioid is an opioid agonist. In an embodiment, the opioid is morphine, fentanyl, oxymorphone, buprenorphine, hydromorphone, oxycodone, hydrocodone, diamorphine (i.e., heroin) or the like. In another embodiment, the opioid is oxycodone or diamorphine. In another embodiment, the opioid is buprenorphine.

Also provided herein is a method of preventing alcohol dependence in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof.

Also provided herein is a method of treating alcohol use disorder in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof. In another embodiment, the alcohol use disorder is moderate to severe alcohol use disorder.

Also provided herein is a method for the blockade of the effects of exogenously administered opioids in a subject in need thereof comprising administering to the subject a compound of Formula I or II, or a pharmaceutically acceptable salt thereof. In an embodiment, the opioid is an opioid agonist. In an embodiment, the opioid is morphine, fentanyl, oxymorphone, buprenorphine, hydromorphone, oxycodone, hydrocodone, diamorphine (i.e., heroin) or the like. In another embodiment, the opioid is oxycodone or diamorphine. In another embodiment, the opioid is buprenorphine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the powder x-ray diffraction (PXRD) pattern for Compound 2.

DETAILED DESCRIPTION OF THE INVENTION

One of the challenges for delivering an active pharmaceutical ingredient (API) in a long-acting injectable composition is incorporating a sufficient amount of drug to maintain effective plasma levels of API over an extended period of time (e.g., several weeks or months) while maintaining a total composition volume that can be readily injected, in a single injection, into a subject. This challenge becomes still more difficult when the API is in the form of a prodrug, and thus having a molecular weight higher than the parent API. Further, the physicochemical properties of such a prodrug (including, but not limited to, chemical stability, physical stability, physical form and solubility) are important to its suitability for a long-acting injectable composition.

Such long-acting injectable compositions can be in the form of a suspension of solids in an aqueous (liquid) composition. For example, a suspension of a prodrug of an API in an aqueous composition can be prepared for a long-acting composition. In such a system, the physicochemical properties of the prodrug, including crystallinity and solubility of the solid material, are important to its ability to deliver drug over an extended duration and with a therapeutic plasma concentration. In particular, crystalline prodrugs with low aqueous solubility are important for long-acting injectable suspensions.

Provided herein are novel compounds which are prodrugs of naltrexone (NTX) having one or two covalently-attached naltrexone molecules, related methods of treating or preventing opioid dependence or alcohol dependence by administering one or more compounds of the invention, synthetic methods for making the compounds of the invention, and pharmaceutical compositions containing compounds of the invention.

In a non-limiting aspect, the compounds of the present invention may undergo enzyme-mediated cleavage under physiological conditions to release the naltrexone parent drug. In one embodiment, the ultimate release of the naltrexone parent drug is controlled by the rate of dissolution of a crystalline compound of Formula I or II.

Definitions

Listed below are definitions of various terms used to describe this invention. These definitions apply to the terms as they are used throughout this specification and claims, unless otherwise limited in specific instances, either individually or as part of a larger group.

Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein and the laboratory procedures in cell culture, molecular genetics, organic chemistry, and peptide chemistry are those well-known and commonly employed in the art.

As used herein, the term “about” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which it is used. As used herein when referring to a measurable value such as an amount, a temporal duration, and the like, the term “about” is meant to encompass variations of ±10%, including ±5%, ±1%, and ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

As used herein, “opioid dependence” is generally defined as a chronic brain disease that causes compulsive drug seeking and use.

As used herein, “alcohol dependence” is generally defined as a chronic brain disease that causes compulsive alcohol seeking and use.

As used herein, “alcohol use disorder” is generally defined as encompassing the disorders of alcohol dependence and alcohol abuse and can be classified as mild, moderate or severe.

As used herein, the terms “treat,” “treated,” “treating,” or “treatment” includes the diminishment or alleviation of at least one symptom associated or caused by the state, disorder or disease being treated.

As used herein, the terms “prevent,” “preventing,” or “prevention” means no disorder or disease development if none had occurred, or no further disorder or disease development if there had already been development of the disorder or disease. Also considered is the ability of one to prevent some or all of the symptoms associated with the disorder or disease.

As used herein, the terms “patient,” “individual” or “subject” refer to a human.

As used herein, the terms “effective amount,” “pharmaceutically effective amount,” and “therapeutically effective amount” refer to a nontoxic but sufficient amount of an agent to provide the desired biological result. That result may be reduction or alleviation of the signs, symptoms, or causes of a disease, or any other desired alteration of a biological system. An appropriate therapeutic amount in any individual case may be determined by one of ordinary skill in the art using routine experimentation.

As used herein, the term “pharmaceutically acceptable” refers to a material, such as a carrier or diluent, which does not abrogate the biological activity or properties of the compound, and is relatively non-toxic, i.e., the material may be administered to an individual without causing undesirable biological effects or interacting in a deleterious manner with any of the components of the composition in which it is contained.

As used herein, the term “pharmaceutically acceptable salt” refers to derivatives of a compound of the invention wherein the compound is modified by converting an existing acid or base moiety to its salt form. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as carboxylic acids; and the like. The pharmaceutically acceptable salts of the present invention include the conventional non-toxic salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. The pharmaceutically acceptable salts of the present invention can be synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts can be prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. The phrase “pharmaceutically acceptable salt” is not limited to a mono, or 1:1, salt. For example, “pharmaceutically acceptable salt” also includes bis-salts, such as a bis-hydrochloride salt. Lists of suitable salts are found in Remington's Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, p. 1418 and Journal of Pharmaceutical Science, 66, 2 (1977), each of which is incorporated herein by reference in its entirety.

As used herein, the term “composition” or “pharmaceutical composition” refers to a mixture of at least one compound useful within the invention with a pharmaceutically acceptable carrier. The pharmaceutical composition facilitates administration of the compound to a patient or subject. Multiple techniques of administering a compound exist in the art including, but not limited to, intravenous, oral, aerosol, parenteral, ophthalmic, pulmonary, and topical administration.

As used herein, the term “pharmaceutically acceptable carrier” includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration, such as sterile pyrogen-free water. Suitable carriers are described in Remington's Pharmaceutical Sciences (Genaro, Ed., Mack Publishing Co., 1985, Easton, Pa.), which is incorporated herein by reference. Preferred examples of such carriers or diluents include, but are not limited to, water, saline, finger's solutions, dextrose solution, and 5% human serum albumin. Liposomes and non-aqueous vehicles such as fixed oils may also be used. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the pharmaceutical compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions. The pharmaceutical compositions can also advantageously employ a density enhancing agent, such as a sugar, e.g., mannitol, or sorbitol and/or a tonicity adjusting agent, such as sodium chloride or glycerol. Other pharmaceutical carriers that could be used in the pharmaceutical compositions provided herein also include aqueous methylcellulose solutions, fructose solution, ethanol, or oils of animal, vegetative, or synthetic origin. The pharmaceutically acceptable carrier may also contain preservatives, and buffers as are known in the art.

As used herein, the term “alkyl,” by itself or as part of another substituent, means a straight or branched chain hydrocarbon having the number of carbon atoms designated (i.e., C₁-C₄ alkyl means an alkyl having one to four carbon atoms) and includes straight and branched chains. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl.

As used herein, the term “alkoxy,” by itself or as part of another substituent, refers to the group —O-alkyl, wherein alkyl is as defined herein. Alkoxy includes, by way of example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, t-butoxy and the like.

As used herein, the term “alkylcarbonyloxy,” by itself or as part of another substituent, refers to the group —O—C(═O)-alkyl, wherein alkyl is as defined herein. Alkylcarbonyloxy includes, by way of example, acetate, propionate, butyrate, methylbutanoate, pentanoate and the like.

As used herein, the term “halogen” alone or as part of another substituent means a fluorine, chlorine, bromine, or iodine atom, preferably, fluorine, chlorine, or bromine, more preferably, fluorine or chlorine.

Compounds of the Invention

In one embodiment, a compound of the invention has the structure of Formula I:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4;

wherein the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound with points of attachment selected from the 1 and 1′ positions, the 1 and 4′ positions, the 2 and 2′ positions, or the 2 and 3′ positions; and

further wherein the R groups are bound with points of attachment as follows:

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 1 and 1′ positions, then the R groups are bound at the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions;

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 1 and 4′ positions, then the R groups are bound at the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions;

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 2 and 2′ positions, then the R groups are bound at the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions; or

when the —(CH₂)_(z)C(═O)O-naltrexone moieties are bound at the 2 and 3′ positions, then the R groups are bound at the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula I, both R groups are hydrogen.

In another embodiment of Formula I, both R groups are halogen.

In another embodiment of Formula I, both R groups are fluorine.

In another embodiment of Formula I, both R groups are chlorine.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula I, both R groups are methyl.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula I, both R groups are methoxy.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula I, both R groups are methylcarbonyloxy.

In another embodiment of Formula I, both values of z are 1.

In another embodiment of Formula I, both values of z are 2.

In another embodiment of Formula I, both values of z are 3.

In another embodiment of Formula I, both values of z are 4.

In another embodiment of Formula I, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula I, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula I, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula I, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula I, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula I, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula I, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula I, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula I, both R groups are methyl and both values of z are 1.

In another embodiment of Formula I, both R groups are methyl and both values of z are 2.

In another embodiment of Formula I, both R groups are methyl and both values of z are 3.

In another embodiment of Formula I, both R groups are methyl and both values of z are 4.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula I, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula I, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula I, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula I, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula I, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula I, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula I, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula I, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula I, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula I, a compound of Formula Ia has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions.

In another embodiment of Formula Ia, the R groups are bound with points of attachment at the 2 and 2′ positions.

In another embodiment of Formula Ia, the R groups are bound with points of attachment at the 3 and 3′ positions.

In another embodiment of Formula Ia, the R groups are bound with points of attachment at the 4 and 4′ positions.

In another embodiment of Formula Ia, both R groups are hydrogen.

In another embodiment of Formula Ia, both R groups are halogen.

In another embodiment of Formula Ia, both R groups are fluorine.

In another embodiment of Formula Ia, both R groups are chlorine.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula Ia, both R groups are methyl.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula Ia, both R groups are methoxy.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula Ia, both R groups are methylcarbonyloxy.

In another embodiment of Formula Ia, both values of z are 1.

In another embodiment of Formula Ia, both values of z are 2.

In another embodiment of Formula Ia, both values of z are 3.

In another embodiment of Formula Ia, both values of z are 4.

In another embodiment of Formula Ia, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula Ia, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula Ia, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula Ia, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula Ia, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula Ia, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula Ia, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ia, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula Ia, both R groups are methyl and both values of z are 1.

In another embodiment of Formula Ia, both R groups are methyl and both values of z are 2.

In another embodiment of Formula Ia, both R groups are methyl and both values of z are 3.

In another embodiment of Formula Ia, both R groups are methyl and both values of z are 4.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula Ia, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula Ia, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ia, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula Ia, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ia, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ia, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ia, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula I, a compound of Formula Ib has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions.

In another embodiment of Formula Ib, the R groups are bound with points of attachment at the 1 and 1′ positions.

In another embodiment of Formula Ib, the R groups are bound with points of attachment at the 3 and 3′ positions.

In another embodiment of Formula Ib, the R groups are bound with points of attachment at the 4 and 4′ positions.

In another embodiment of Formula Ib, both R groups are hydrogen.

In another embodiment of Formula Ib, both R groups are halogen.

In another embodiment of Formula Ib, both R groups are fluorine.

In another embodiment of Formula Ib, both R groups are chlorine.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula Ib, both R groups are methyl.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula Ib, both R groups are methoxy.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula Ib, both R groups are methylcarbonyloxy.

In another embodiment of Formula Ib, both values of z are 1.

In another embodiment of Formula Ib, both values of z are 2.

In another embodiment of Formula Ib, both values of z are 3.

In another embodiment of Formula Ib, both values of z are 4.

In another embodiment of Formula Ib, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula Ib, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula Ib, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula Ib, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula Ib, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula Ib, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula Ib, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ib, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula Ib, both R groups are methyl and both values of z are 1.

In another embodiment of Formula Ib, both R groups are methyl and both values of z are 2.

In another embodiment of Formula Ib, both R groups are methyl and both values of z are 3.

In another embodiment of Formula Ib, both R groups are methyl and both values of z are 4.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula Ib, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula Ib, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ib, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula Ib, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ib, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ib, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ib, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula I, a compound of Formula Ic has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula Ic, the R groups are bound with points of attachment at the 2 and 3′ positions.

In another embodiment of Formula Ic, the R groups are bound with points of attachment at the 3 and 2′ positions.

In another embodiment of Formula Ic, the R groups are bound with points of attachment at the 4 and 1′ positions.

In another embodiment of Formula Ic, both R groups are hydrogen.

In another embodiment of Formula Ic, both R groups are halogen.

In another embodiment of Formula Ic, both R groups are fluorine.

In another embodiment of Formula Ic, both R groups are chlorine.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula Ic, both R groups are methyl.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula Ic, both R groups are methoxy.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula Ic, both R groups are methylcarbonyloxy.

In another embodiment of Formula Ic, both values of z are 1.

In another embodiment of Formula Ic, both values of z are 2.

In another embodiment of Formula Ic, both values of z are 3.

In another embodiment of Formula Ic, both values of z are 4.

In another embodiment of Formula Ic, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula Ic, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula Ic, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula Ic, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula Ic, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula Ic, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula Ic, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ic, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula Ic, both R groups are methyl and both values of z are 1.

In another embodiment of Formula Ic, both R groups are methyl and both values of z are 2.

In another embodiment of Formula Ic, both R groups are methyl and both values of z are 3.

In another embodiment of Formula Ic, both R groups are methyl and both values of z are 4.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula Ic, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula Ic, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ic, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula Ic, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Ic, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Ic, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Ic, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula I, a compound of Formula Id has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula Id, the R groups are bound with points of attachment at the 1 and 4′ positions.

In another embodiment of Formula Id, the R groups are bound with points of attachment at the 3 and 2′ positions.

In another embodiment of Formula Id, the R groups are bound with points of attachment at the 4 and 1′ positions.

In another embodiment of Formula Id, both R groups are hydrogen.

In another embodiment of Formula Id, both R groups are halogen.

In another embodiment of Formula Id, both R groups are fluorine.

In another embodiment of Formula Id, both R groups are chlorine.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula Id, both R groups are methyl.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula Id, both R groups are methoxy.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula Id, both R groups are methylcarbonyloxy.

In another embodiment of Formula Id, both values of z are 1.

In another embodiment of Formula Id, both values of z are 2.

In another embodiment of Formula Id, both values of z are 3.

In another embodiment of Formula Id, both values of z are 4.

In another embodiment of Formula Id, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula Id, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula Id, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula Id, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula Id, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula Id, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula Id, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Id, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula Id, both R groups are methyl and both values of z are 1.

In another embodiment of Formula Id, both R groups are methyl and both values of z are 2.

In another embodiment of Formula Id, both R groups are methyl and both values of z are 3.

In another embodiment of Formula Id, both R groups are methyl and both values of z are 4.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula Id, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula Id, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Id, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula Id, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula Id, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula Id, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula Id, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment, a compound of the invention has the structure of Formula II:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4;

-   -   wherein the —(CH₂)_(z)C(═O)OH moiety and the         —(CH₂)_(z)C(═O)O-naltrexone moiety are bound with points of         attachment selected from the 1 and 1′ positions, the 1 and 4′         positions, the 2 and 2′ positions, or the 2 and 3′ positions;         and

further wherein the R groups are bound with points of attachment as follows:

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 1 and 1′ positions, then the R groups are bound at the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions;

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 1 and 4′ positions, then the R groups are bound at the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions;

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 2 and 2′ positions, then the R groups are bound at the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions; or

when the —(CH₂)_(z)C(═O)OH moiety and the —(CH₂)_(z)C(═O)O-naltrexone moiety are bound at the 2 and 3′ positions, then the R groups are bound at the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula II, both R groups are hydrogen.

In another embodiment of Formula II, both R groups are halogen.

In another embodiment of Formula II, both R groups are fluorine.

In another embodiment of Formula II, both R groups are chlorine.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula II, both R groups are methyl.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula II, both R groups are methoxy.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula II, both R groups are methylcarbonyloxy.

In another embodiment of Formula II, both values of z are 1.

In another embodiment of Formula II, both values of z are 2.

In another embodiment of Formula II, both values of z are 3.

In another embodiment of Formula II, both values of z are 4.

In another embodiment of Formula II, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula II, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula II, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula II, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula II, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula II, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula II, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula II, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula II, both R groups are methyl and both values of z are 1.

In another embodiment of Formula II, both R groups are methyl and both values of z are 2.

In another embodiment of Formula II, both R groups are methyl and both values of z are 3.

In another embodiment of Formula II, both R groups are methyl and both values of z are 4.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula II, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula II, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula II, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula II, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula II, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula II, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula II, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula II, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula II, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula II, a compound of Formula IIa has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 2 and 2′ positions, the 3 and 3′ positions, or the 4 and 4′ positions.

In another embodiment of Formula IIa, the R groups are bound with points of attachment at the 2 and 2′ positions.

In another embodiment of Formula IIa, the R groups are bound with points of attachment at the 3 and 3′ positions.

In another embodiment of Formula IIa, the R groups are bound with points of attachment at the 4 and 4′ positions.

In another embodiment of Formula IIa, both R groups are hydrogen.

In another embodiment of Formula IIa, both R groups are halogen.

In another embodiment of Formula IIa, both R groups are fluorine.

In another embodiment of Formula IIa, both R groups are chlorine.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula IIa, both R groups are methyl.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula IIa, both R groups are methoxy.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula IIa, both R groups are methylcarbonyloxy.

In another embodiment of Formula IIa, both values of z are 1.

In another embodiment of Formula IIa, both values of z are 2.

In another embodiment of Formula IIa, both values of z are 3.

In another embodiment of Formula IIa, both values of z are 4.

In another embodiment of Formula IIa, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula IIa, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula IIa, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula IIa, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula IIa, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula IIa, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula IIa, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIa, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula IIa, both R groups are methyl and both values of z are 1.

In another embodiment of Formula IIa, both R groups are methyl and both values of z are 2.

In another embodiment of Formula IIa, both R groups are methyl and both values of z are 3.

In another embodiment of Formula IIa, both R groups are methyl and both values of z are 4.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula IIa, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula IIa, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIa, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula IIa, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIa, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIa, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIa, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula II, a compound of Formula IIb has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions.

In another embodiment of Formula IIb, the R groups are bound with points of attachment at the 1 and 1′ positions.

In another embodiment of Formula IIb, the R groups are bound with points of attachment at the 3 and 3′ positions.

In another embodiment of Formula IIb, the R groups are bound with points of attachment at the 4 and 4′ positions.

In another embodiment of Formula IIb, both R groups are hydrogen.

In another embodiment of Formula IIb, both R groups are halogen.

In another embodiment of Formula IIb, both R groups are fluorine.

In another embodiment of Formula IIb, both R groups are chlorine.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula IIb, both R groups are methyl.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula IIb, both R groups are methoxy.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula IIb, both R groups are methylcarbonyloxy.

In another embodiment of Formula IIb, both values of z are 1.

In another embodiment of Formula IIb, both values of z are 2.

In another embodiment of Formula IIb, both values of z are 3.

In another embodiment of Formula IIb, both values of z are 4.

In another embodiment of Formula IIb, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula IIb, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula IIb, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula IIb, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula IIb, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula IIb, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula IIb, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIb, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula IIb, both R groups are methyl and both values of z are 1.

In another embodiment of Formula IIb, both R groups are methyl and both values of z are 2.

In another embodiment of Formula IIb, both R groups are methyl and both values of z are 3.

In another embodiment of Formula IIb, both R groups are methyl and both values of z are 4.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula IIb, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula IIb, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIb, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula IIb, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIb, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIb, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIb, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula II, a compound of Formula IIc has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 2 and 3′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula IIc, the R groups are bound with points of attachment at the 2 and 3′ positions.

In another embodiment of Formula IIc, the R groups are bound with points of attachment at the 3 and 2′ positions.

In another embodiment of Formula IIc, the R groups are bound with points of attachment at the 4 and 1′ positions.

In another embodiment of Formula IIc, both R groups are hydrogen.

In another embodiment of Formula IIc, both R groups are halogen.

In another embodiment of Formula IIc, both R groups are fluorine.

In another embodiment of Formula IIc, both R groups are chlorine.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkyl. In another embodiment of Formula IIc, both R groups are methyl.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula IIc, both R groups are methoxy.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula IIc, both R groups are methylcarbonyloxy.

In another embodiment of Formula IIc, both values of z are 1.

In another embodiment of Formula IIc, both values of z are 2.

In another embodiment of Formula IIc, both values of z are 3.

In another embodiment of Formula IIc, both values of z are 4.

In another embodiment of Formula IIc, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula IIc, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula IIc, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula IIc, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula IIc, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula IIc, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula IIc, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIc, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula IIc, both R groups are methyl and both values of z are 1.

In another embodiment of Formula IIc, both R groups are methyl and both values of z are 2.

In another embodiment of Formula IIc, both R groups are methyl and both values of z are 3.

In another embodiment of Formula IIc, both R groups are methyl and both values of z are 4.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula IIc, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula IIc, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIc, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula IIc, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IIc, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IIc, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IIc, both R groups are methylcarbonyloxy and both values of z are 4.

In another embodiment of Formula II, a compound of Formula IId has the structure:

or a pharmaceutically acceptable salt thereof;

wherein:

both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy;

both values of z, always being the same, are 1, 2, 3, or 4; and

wherein the R groups are bound with points of attachment selected from the 1 and 4′ positions, the 3 and 2′ positions, or the 4 and 1′ positions.

In another embodiment of Formula IId, the R groups are bound with points of attachment at the 1 and 4′ positions.

In another embodiment of Formula IId, the R groups are bound with points of attachment at the 3 and 2′ positions.

In another embodiment of Formula IId, the R groups are bound with points of attachment at the 4 and 1′ positions.

In another embodiment of Formula IId, both R groups are hydrogen.

In another embodiment of Formula IId, both R groups are halogen.

In another embodiment of Formula IId, both R groups are fluorine.

In another embodiment of Formula IId, both R groups are chlorine.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkyl.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkyl.

In another embodiment of Formula IId, both R groups are methyl.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkoxy.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkoxy.

In another embodiment of Formula IId, both R groups are methoxy.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy.

In another embodiment of Formula IId, both R groups are methylcarbonyloxy.

In another embodiment of Formula IId, both values of z are 1.

In another embodiment of Formula IId, both values of z are 2.

In another embodiment of Formula IId, both values of z are 3.

In another embodiment of Formula IId, both values of z are 4.

In another embodiment of Formula IId, both values of z, always being the same, are 1, 2 or 3.

In another embodiment of Formula IId, both values of z, always being the same, are 1 or 2.

In another embodiment of Formula IId, both R groups are hydrogen and both values of z are 1.

In another embodiment of Formula IId, both R groups are hydrogen and both values of z are 2.

In another embodiment of Formula IId, both R groups are hydrogen and both values of z are 3.

In another embodiment of Formula IId, both R groups are hydrogen and both values of z are 4.

In another embodiment of Formula IId, both R groups are halogen and both values of z are 1. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IId, both R groups are halogen and both values of z are 2. For example, both R groups are chlorine. For example, both R groups are fluorine.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkyl and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 3.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkyl and both values of z are 4.

In another embodiment of Formula IId, both R groups are methyl and both values of z are 1.

In another embodiment of Formula IId, both R groups are methyl and both values of z are 2.

In another embodiment of Formula IId, both R groups are methyl and both values of z are 3.

In another embodiment of Formula IId, both R groups are methyl and both values of z are 4.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkoxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 3.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkoxy and both values of z are 4.

In another embodiment of Formula IId, both R groups are methoxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are methoxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are methoxy and both values of z are 3.

In another embodiment of Formula IId, both R groups are methoxy and both values of z are 4.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₄ alkcarbonyloxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IId, both R groups are unsubstituted C₁-C₂ alkylcarbonyloxy and both values of z are 4.

In another embodiment of Formula IId, both R groups are methylcarbonyloxy and both values of z are 1.

In another embodiment of Formula IId, both R groups are methylcarbonyloxy and both values of z are 2.

In another embodiment of Formula IId, both R groups are methylcarbonyloxy and both values of z are 3.

In another embodiment of Formula IId, both R groups are methylcarbonyloxy and both values of z are 4.

The compounds of Formula I are dimeric compounds, each containing two molecules of naltrexone covalently bound to a pro-moiety. Accordingly, in another embodiment, a compound of Formula I, for example a compound of Formula Ia, Ib, Ic or Id, or a pharmaceutically acceptable salt thereof, is administered to a subject and metabolized in vivo to release naltrexone and an intermediate depicted as a compound of Formula II. The resultant compound of Formula II, for example a compound of Formula IIa, IIb, IIc or IId, or a pharmaceutically acceptable salt thereof, may also be metabolized in vivo to release naltrexone. In another embodiment, a compound of Formula II, for example a compound of Formula IIa, IIb, IIc or IId, or a pharmaceutically acceptable salt thereof, is administered to a subject and metabolized in vivo to release naltrexone.

Certain embodiments of compounds of Formula I or II are shown below in Tables A and B, respectively. Compounds of Formulas I or II, or pharmaceutically acceptable salts thereof, and compounds of Tables A and B, are sometimes referred to herein as “compounds of the invention,” or “compounds provided herein.”

TABLE A Compound Structure  1

 2

 3

 4

 5

 6

 7

 8

 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

TABLE B Compound Structure  1i

 2i

 3i

 4i

 5i

 6i

 7i

 8i

 9i

10i

11i

12i

13i

14i

15i

16i

17i

18i

19i

20i

21i

22i

23i

24i

25i

26i

Also provided herein are pharmaceutical compositions comprising a compound of Formula I or II, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. In one embodiment, the composition is administered to a subject in need of the treatment of opioid dependence. In another embodiment, the composition is administered to a subject in need of the treatment of alcohol dependence. In another embodiment, the composition is administered to a subject in need of the treatment of alcohol use disorder. In another embodiment, the composition is administered to a subject in need of the prevention of opioid dependence. In another embodiment, the composition is administered to a subject in need of the prevention of relapse to opioid dependence. In another embodiment, the composition is administered to a subject in need of the prevention of alcohol dependence.

In any of the compositions or methods as described herein, the compound of Formula I or II, or a pharmaceutically acceptable salt thereof, is present and/or administered in a therapeutically effective amount.

In any of the compositions or methods as described herein, the compound of Formula Ia, Ib, Ic, Id, IIa, IIb, IIc or IId, or a pharmaceutically acceptable salt thereof, is present and/or administered in a therapeutically effective amount.

In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is converted to one equivalent of naltrexone and one equivalent of a compound of Formula II, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is converted to up to one equivalent of naltrexone and up to one equivalent of a compound of Formula II, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is converted to from about 0.6 to 0.95 equivalents of naltrexone and a compound of Formula II, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is converted to from about 0.7 to 0.95 equivalents of naltrexone and a compound of Formula II, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is converted to from about 0.8 to 0.95 equivalents of naltrexone and a compound of Formula II, upon parenteral administration. For example, about 0.7 equivalents, about 0.75 equivalents, about 0.8 equivalents, about 0.85 equivalents, about 0.9 equivalents, about 0.95 equivalents, or greater than 0.95 equivalents of the total dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, administered is converted to naltrexone and a compound of Formula II upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is essentially completely converted to naltrexone and a compound of Formula II, upon parenteral administration. In another embodiment, the parenteral administration is via the intramuscular route.

In another embodiment, the resultant compound of Formula II is converted in vivo to one equivalent of naltrexone. In another embodiment, the resultant compound of Formula II is converted in vivo to up to one equivalent of naltrexone. For example, about 0.5 equivalents, about 0.6 equivalents, about 0.7 equivalents, about 0.75 equivalents, about 0.8 equivalents, about 0.85 equivalents, about 0.9 equivalents, about 0.95 equivalents, or greater than 0.95 equivalents of the total amount of a compound of Formula II is converted to naltrexone. In another embodiment, the compound of Formula II is essentially completely converted to naltrexone.

In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, may be converted in vivo to two equivalents of naltrexone, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, may be converted to up to two equivalents of naltrexone, upon parenteral administration. For example, about 1.2 equivalents, about 1.3 equivalents, about 1.4 equivalents, about 1.5 equivalents, about 1.6 equivalents, about 1.7 equivalents, about 1.8 equivalents, or greater than 1.8 equivalents of the total dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, administered is converted to naltrexone, upon parenteral administration. In another embodiment, a compound of Formula I, or a pharmaceutically acceptable salt thereof, is essentially completely converted to naltrexone, upon parenteral administration. In another embodiment, the parenteral administration is via the intramuscular route.

In another embodiment, any one of the compounds 1 to 26 (see Table A), or a pharmaceutically acceptable salt thereof, may be converted in vivo to two equivalents of naltrexone, upon parenteral administration. In another embodiment, any one of the compounds 1 to 26, or a pharmaceutically acceptable salt thereof, may be converted in vivo to up to two equivalents of naltrexone, upon parenteral administration. For example, about 1.2 equivalents, about 1.3 equivalents, about 1.4 equivalents, about 1.5 equivalents, about 1.6 equivalents, about 1.7 equivalents, about 1.8 equivalents, or greater than 1.8 equivalents of the total dose of any one of the compounds 1 to 26, or a pharmaceutically acceptable salt thereof, administered is converted to naltrexone, upon parenteral administration. In another embodiment, any one of the compounds 1 to 26, or a pharmaceutically acceptable salt thereof, is essentially completely converted to naltrexone, upon parenteral administration. In another embodiment, the parenteral administration is via the intramuscular route.

In another embodiment, any one of the compounds 1i to 26i (see Table B) may be converted in vivo to one equivalent of naltrexone. In another embodiment, any one of the compounds 1i to 26i may be converted in vivo to up to one equivalent of naltrexone. For example, about 0.7 equivalents, about 0.75 equivalents, about 0.8 equivalents, about 0.85 equivalents, about 0.9 equivalents, about 0.95 equivalents, or greater than 0.95 equivalents of the total amount of any one of the compounds 1i to 26i is converted to naltrexone. In another embodiment, any one of the compounds 1i to 26i is essentially completely converted to naltrexone.

Compounds described herein also include isotopically-labeled compounds wherein one or more atoms is replaced by an atom having the same atomic number, but an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes suitable for inclusion in the compounds described herein include and are not limited to ²H, ³H, ¹¹C, ¹³C, ¹⁴C, ³⁶Cl, ¹⁸F, ¹²³I, ¹²⁵I, ¹³N, ¹⁵N, ¹⁵O, ¹⁷O, ¹⁸O, ³²P, and ³⁵S. In one embodiment, isotopically-labeled compounds are useful in drug or substrate tissue distribution studies. In another embodiment, substitution with heavier isotopes such as deuterium affords greater metabolic stability (for example, increased in vivo half-life or reduced dosage requirements). In another embodiment, the compounds described herein include a ²H (i.e., deuterium) isotope. Isotopically-labeled compounds are prepared by any suitable method or by processes using an appropriate isotopically-labeled reagent in place of the non-labeled reagent otherwise employed.

Methods of Treatment

The compounds of the invention can be used in a method of treating a disease or condition in a subject wherein treatment with a compound of the invention would be beneficial, said method comprising administering to the subject a compound of the invention, or a pharmaceutical composition comprising a compound of the invention.

The compounds of the invention can be used to treat a disease or condition selected from the group consisting of opioid dependence or alcohol dependence in a subject in need thereof.

The compounds of the invention can be used to prevent a disease or condition selected from the group consisting of opioid dependence, relapse to opioid dependence, or alcohol dependence in a subject in need thereof.

In one embodiment, the compounds of the invention can be used to treat opioid dependence in a subject in need thereof.

In another embodiment, the compounds of the invention can be used to treat alcohol dependence in a subject in need thereof.

In another embodiment, the compounds of the invention can be used to treat alcohol use disorder in a subject in need thereof.

In yet another embodiment, the compounds of the invention can be used to prevent opioid dependence in a subject in need thereof.

In yet another embodiment, the compounds of the invention can be used to prevent relapse to opioid dependence in a subject in need thereof.

In another embodiment, the compounds of the invention can be used to prevent alcohol dependence in a subject in need thereof.

In another embodiment, the compounds of the invention can be used to treat addiction in a subject in need thereof. The addiction can be drug addiction or alcohol addiction.

The drug addiction can be one or more of opioid addiction (i.e., opioid dependence) or stimulant addiction. The opioid can be one or more of fentanyl, morphine, oxymorphone, buprenorphine, hydromorphone, oxycodone, hydrocodone, or the like. The drug addiction can also be one or more of diamorphine (i.e., heroin), cocaine, nicotine, and amphetamine.

In one embodiment, compounds of the invention can be used to treat a disease or condition in a subject, wherein the subject has a tolerance to opioid medication, the subject has a history of opioid dependency or abuse, the subject is at risk of opioid dependency or abuse, or in circumstances wherein it is desirable that the risk of opioid dependence or opioid addiction in the subject is minimized.

The compounds of the invention can also be used to treat alcohol addiction, which can also be referred to as alcoholism. “Alcoholism” refers to an addictive disease or disorder characterized by an inability to control the intake of alcohol, i.e., a continued excessive or compulsive use of alcoholic drinks. Alcoholism may involve changes an individual's ability to metabolize alcohol as well. Diagnosis of alcoholism can be made by psychiatric examination.

In one aspect, the compounds provided herein are useful in treatment or prevention of opioid dependence or alcohol dependence by being converted in vivo into naltrexone, which acts as an antagonist of the μ-opioid receptor.

In one embodiment of the methods described herein, the subject is human.

Administration/Dosage/Formulations

The compounds of the invention enable compositions with desirable properties and advantages. For example, the compositions can be administered once per month, or once per two months, or once per three months, which is particularly desirable for the subjects described herein. Such compositions can provide many therapeutic benefits that are not achieved with corresponding shorter acting, or immediate-release oral preparations of naltrexone. For example, the composition can maintain lower, more steady plasma concentrations of naltrexone.

In one embodiment, the compound of the invention is administered in a composition suitable for parenteral administration. In another embodiment, the parenteral administration is by injection. In another embodiment, the parenteral administration is by intramuscular injection. Injectable preparations, for example, sterile injectable aqueous or oleaginous suspensions, may be formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable suspension or emulsion, such as INTRALIPID®, LIPOSYN® or OMEGAVEN®, or solution, in a nontoxic parenterally acceptable diluent or solvent, for example, as a solution in 1,3-butanediol. INTRALIPID® is an intravenous fat emulsion containing 10-30% soybean oil, 1-10% egg yolk phospholipids, 1-10% glycerin and water. LIPOSYN® is also an intravenous fat emulsion containing 2-15% safflower oil, 2-15% soybean oil, 0.5-5% egg phosphatides 1-10% glycerin and water. OMEGAVEN® is an emulsion for infusion containing about 5-25% fish oil, 0.5-10% egg phosphatides, 1-10% glycerin and water. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, USP and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil can be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid are used in the preparation of injectables.

The injectable formulations can be sterilized, for example, by filtration through a bacterial-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions which can be dissolved or dispersed in sterile water or other sterile injectable medium prior to use.

In one embodiment, a pharmaceutical composition in accordance with the invention may be accomplished by the use of a liquid suspension of crystalline or amorphous material with poor water solubility. In another embodiment, the material is crystalline.

In another embodiment, a pharmaceutical composition may be accomplished by dissolving or suspending the compound of the invention in an oil vehicle.

In another embodiment, a pharmaceutical composition may be accomplished by forming microencapsule matrices of the compound of the invention in biodegradable polymers such as polylactide-polyglycolide. Depending upon the ratio of compound to polymer and the nature of the particular polymer employed, the rate of compound release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Injectable compositions are also prepared by entrapping the compound in liposomes or microemulsions that are compatible with body tissues.

In another aspect, provided herein is a pharmaceutical composition comprising at least one compound of the invention, together with a pharmaceutically acceptable carrier.

Actual dosage levels of the active ingredients in the pharmaceutical compositions of this invention may be varied so as to obtain an amount of the active ingredient that is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being toxic to the patient.

In particular, the selected dosage level will depend upon a variety of factors including the rate of metabolism of the particular compound employed, the rate of clearance of the compound, the duration of the treatment, other drugs, compounds or materials used in combination with the compound, the age, sex, weight, condition, general health and prior medical history of the patient being treated, and like factors well known in the medical arts.

A medical doctor, e.g., physician, having ordinary skill in the art may readily determine and prescribe the effective amount of the pharmaceutical composition required. For example, the physician could begin administration of the pharmaceutical composition to dose a compound of the invention at levels lower than that required in order to achieve the desired therapeutic effect and gradually increase the dosage until the desired effect is achieved.

In particular embodiments, it is especially advantageous to formulate the compound in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subjects to be treated; each unit containing a predetermined quantity of the compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical vehicle. The dosage unit forms of the invention are dictated by and directly dependent on (a) the unique characteristics of the compound and the particular therapeutic effect to be achieved, and (b) the limitations inherent in the art of compounding/formulating such a compound for the treatment or prevention of opioid dependence or alcohol dependence in a subject.

In one embodiment, the compounds of the invention are formulated using one or more pharmaceutically acceptable carriers. In one embodiment, the pharmaceutical compositions of the invention comprise a therapeutically effective amount of a compound of the invention and a pharmaceutically acceptable carrier.

In some embodiments, a single dose of a compound of Formula I or II, or a pharmaceutically acceptable salt thereof, is from about 1 mg to about 5,000 mg. In some embodiments, a single dose of a compound used in compositions described herein is less than about 2,000 mg, or less than about 1,800 mg, or less than about 1,600 mg, or less than about 1,400 mg, or less than about 1,300 mg, or less than about 1,200 mg, or less than about 1,100 mg, or less than about 1,000 mg, or less than about 900 mg, or less than about 800 mg, or less than about 750 mg, or less than about 700 mg, or less than about 600 mg, or less than about 500 mg, or less than about 300 mg or less than about 100 mg. For example, a single dose is about 100 mg, 200 mg, 250 mg, 300 mg, 350 mg, 400 mg, 450 mg, 500 mg, 550 mg, 600 mg, 650 mg, 700 mg, 750 mg, 800 mg, 850 mg, 900 mg, 950 mg, 1,000 mg, 1,050 mg, 1,100 mg, 1,150 mg, 1,200 mg, 1,250 mg, 1,300 mg, 1,350 mg, 1,400 mg, 1,450 mg, 1,500 mg, 1,550 mg, 1,600 mg, 1,650 mg, 1,700 mg, 1,750 mg, 1,800 mg, 1,850 mg, 1,900 mg 1,950 mg, or about 2,000 mg of a compound of Formula I. In a particular embodiment, the dose is administered as a single parenteral injection. In a specific embodiment, the dose is administered as a single intramuscular injection.

For comparison purposes, VIVITROL® (naltrexone for extended-release injectable suspension) is administered intramuscularly every four weeks or once a month at a dose of 380 mg naltrexone. REVIA® (naltrexone hydrochloride tablets USP) can be administered orally once per day at a dose of 50 mg naltrexone hydrochloride.

In some embodiments, a single intramuscular injection is administered with a dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, of from about 500 mg to about 2,200 mg. In some embodiments, a single intramuscular injection is administered with a dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, of from about 750 mg to about 2,000 mg. In some embodiments, a single intramuscular injection is administered with a dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, of from about 1,000 mg to about 2,000 mg. In some embodiments, a single intramuscular injection is administered with a dose of a compound of Formula I, or a pharmaceutically acceptable salt thereof, of from about 1,200 mg to about 1,800 mg.

In another embodiment, a pharmaceutical composition comprises a compound of Formula I or II or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a duration of release of naltrexone of, from about 1 week to about 15 weeks, following parenteral administration. In another embodiment, the duration of release of naltrexone is from about 2 weeks to about 15 weeks, or from about 4 weeks to about 15 weeks, or from about 6 weeks to about 15 weeks, or from about 8 weeks to about 15 weeks, or from about 8 weeks to about 14 weeks, or from about 8 weeks to about 12 weeks. In another embodiment, the duration of release of naltrexone is about 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, 10 weeks, 11 weeks, 12 weeks, 13 weeks, 14 weeks, or 15 weeks. In another embodiment, the duration of release of naltrexone is about 8 weeks. In another embodiment, the duration of release of naltrexone is about 9 weeks. In another embodiment, the duration of release of naltrexone is about 10 weeks. In another embodiment, the duration of release of naltrexone is about 11 weeks. In another embodiment, the duration of release of naltrexone is about 12 weeks. In another embodiment, the duration of release of naltrexone is about 13 weeks. In another embodiment, the duration of release of naltrexone is about 14 weeks. In another embodiment, the duration of release of naltrexone is about 15 weeks. In another embodiment, the duration of release of naltrexone is about 1 month. In another embodiment, the duration of release of naltrexone is about 2 months. In another embodiment, the duration of release of naltrexone is about 3 months. In another embodiment, the parenteral administration is intramuscular administration.

In another embodiment, a pharmaceutical composition comprises a compound of Formula I or II or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of, from about 0.5 to about 10 ng/mL, following parenteral administration. In another embodiment, the minimum naltrexone blood plasma concentration is at least from about 0.7 to about 10 ng/mL, or from about 0.8 to about 8.0 ng/mL, or from about 1.0 to about 8.0 ng/mL, or from about 1.0 to about 6.0 ng/mL, or from about 1.5 to about 6.0 ng/mL, or from about 1.5 to about 4.0 ng/mL, or from about 1.5 to about 3.0 ng/mL, or from about 1.5 to about 2.5 ng/mL, or from about 1.5 to about 2.0 ng/mL, or from about 2.0 to about 2.5 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 0.5 ng/mL, 0.8 ng/mL, 1.0 ng/mL, 1.1 ng/mL, 1.2 ng/mL, 1.3 ng/mL, 1.4 ng/mL, 1.5 ng/mL, 1.6 ng/mL, 1.7 ng/mL, 1.8 ng/mL, 1.9 ng/mL, 2.0 ng/mL, 2.1 ng/mL, 2.2 ng/mL, 2.3 ng/mL. 2.4 ng/mL, or 2.5 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 1.0 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 1.5 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 2.0 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 2.5 ng/mL. In another embodiment, the minimum naltrexone blood plasma concentration is about 3.0 ng/mL. In another embodiment, the parenteral administration is intramuscular administration.

In other embodiments, a pharmaceutical composition comprises a compound of Formula I or II or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of, from about 0.5 to about 3.0 ng/mL, following parenteral administration, for a duration of, from about 1 week to about 15 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is at least from about 0.7 to about 3.0 ng/mL, or from about 0.8 to about 2.5 ng/mL, or from about 1.0 to about 2.5 ng/mL, or from about 1.0 to about 2.0 ng/mL, or from about 1.0 to about 1.5 ng/mL, or from about 1.5 to about 2.5 ng/mL, or from about 1.5 to about 2.0 ng/mL, for a duration of, from about 1 week to about 15 weeks, or from about 2 weeks to about 14 weeks, or from about 4 weeks to about 14 weeks, or from about 6 weeks to about 14 weeks, or from about 8 weeks to about 12 weeks, or from about 10 weeks to about 12 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 1.0 ng/mL, 1.1 ng/mL, 1.2 ng/mL, 1.3 ng/mL, 1.4 ng/mL, 1.5 ng/mL, 1.6 ng/mL, 1.7 ng/mL, 1.8 ng/mL, 1.9 ng/mL, 2.0 ng/mL, 2.1 ng/mL, 2.2 ng/mL, 2.3 ng/mL. 2.4 ng/mL, or 2.5 ng/mL, for a duration of about 1 week, 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, 12 weeks, or about 14 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 1.0 ng/mL for a duration of about 14 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 1.5 ng/mL for a duration of about 14 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 2.0 ng/mL for a duration of about 14 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 2.0 ng/mL for a duration of about 12 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 2.0 ng/mL for a duration of about 10 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 3.0 ng/mL for a duration of about 10 weeks. In another embodiment, the minimum naltrexone blood plasma concentration is about 3.0 ng/mL for a duration of about 8 weeks. In another embodiment, the parenteral administration is intramuscular administration.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.0 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.5 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 2.0 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.0 ng/mL, following parenteral administration, for a duration of about 12 weeks.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.5 ng/mL, following parenteral administration, for a duration of about 12 weeks.

In another embodiment, a pharmaceutical composition comprises any one of the compounds 1 to 26 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 2.0 ng/mL, following parenteral administration, for a duration of about 12 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.0 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.5 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 2.0 ng/mL, following parenteral administration, for a duration of about 8 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.0 ng/mL, following parenteral administration, for a duration of about 12 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 1.5 ng/mL, following parenteral administration, for a duration of about 12 weeks.

In another embodiment, a pharmaceutical composition comprises Compound 2 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier; wherein the composition provides a minimum naltrexone blood plasma concentration of about 2.0 ng/mL, following parenteral administration, for a duration of about 12 weeks.

Routes of administration of any of the compositions of the invention include oral, nasal, rectal, intravaginal, parenteral, buccal, inhalation spray, sublingual or topical. The compounds for use in the invention may be formulated for administration by any suitable route, such as for oral or parenteral, for example, transdermal, transmucosal (e.g., sublingual, lingual, (trans)buccal, (trans)urethral, vaginal (e.g., trans- and perivaginally), (intra)nasal and (trans)rectal, intravesical, intrapulmonary, intraduodenal, intragastrical, intrathecal, subcutaneous, intramuscular, intradermal, intra-arterial, intravenous, intrabronchial, inhalation, and topical administration. The term parenteral as used herein includes subcutaneous, intracutaneous, intravenous, intramuscular, intraarticular, intraarterial, intrasynovial, intrasternal, intrathecal, intralesional and intracranial injection or infusion techniques. In one embodiment, the parenteral administration is by injection. In another embodiment, the parenteral administration is by intramuscular injection.

Suitable compositions and dosage forms include, for example, tablets, capsules, caplets, pills, gel caps, troches, dispersions, suspensions, solutions, syrups, granules, beads, transdermal patches, gels, powders, pellets, magmas, lozenges, creams, pastes, plasters, lotions, discs, suppositories, liquid sprays for nasal or oral administration, dry powder or aerosolized formulations for inhalation, compositions and formulations for intravesical administration and the like. It should be understood that the formulations and compositions that would be useful in the present invention are not limited to the particular formulations and compositions that are described herein.

For parenteral administration, the compounds of the invention may be formulated for injection or infusion, for example, intravenous, intramuscular or subcutaneous injection or infusion, or for administration in a bolus dose or continuous infusion. Suspensions, solutions or emulsions in an oily or aqueous vehicle, optionally containing other formulatory agents such as suspending, stabilizing or dispersing agents may be used, such as a polysorbate (e.g., polysorbate 20). Other formulatory agents may include preservatives and buffers as are known in the art, such as a phosphate buffer.

It is contemplated that any one of the compounds of the invention can be present as a co-crystal, solvate, hydrate, polymorph, or the like. Further, the compounds of the invention have a defined stereochemistry and one skilled in the art can also envision other enantiomers, diastereoisomers, or racemates of the compounds of the invention.

The present invention provides methods for the synthesis of the compounds of each of the formulae described herein. Compounds of the present invention can be prepared in a variety of ways using commercially available starting materials, compounds known in the literature, or from readily prepared intermediates, by employing standard synthetic methods and procedures either known to those skilled in the art, or which will be apparent to the skilled artisan in light of the teachings herein. The following descriptions of synthetic methods are designed to illustrate, but not to limit, general procedures for the preparation of compounds of the present invention.

General methods for the preparation of compounds as described herein are modified by the use of appropriate reagents and conditions, for the introduction of the various moieties found in the Formulae as provided herein. Compounds described herein are synthesized using any suitable procedures starting from compounds that are available from commercial sources, or are prepared using procedures described herein.

The processes generally provide the desired final compound at or near the end of the overall process, although it may be desirable in certain instances to further convert the compound to a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof.

In the synthetic scheme and examples provided herein, the following abbreviations may be used:

DMF=dimethylformamide

DMAP=4-(dimethylamino)pyridine

DIPEA (DIEA)=N,N-diisopropylethylamine

Pd(dba)₂=bis(dibenzylideneacetone)palladium(0)

Pd₂(dba)₃=tris(dibenzylideneacetone)dipalladium(0)

PyBOP=(benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate

TBS=tert-butyldimethylsilyl

THF=tetrahydrofuran

TFA=trifluoroacetic acid

TEA=triethylamine

TMSOK=potassium trimethylsilanolate

TBME (MTBE)=tert-butyl methyl ether

T₃P=propylphosphonic anhydride

XPhos=2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl.

In one embodiment, a general method for synthesizing one or more compounds of Formula I is provided below (Scheme 1).

As depicted for Compound 2 in Scheme 1 above, the synthesis of one or more compounds of Formula I can be carried out using various synthetic pathways. The common intermediate in every route is 2,2′-(naphthalene-2,6-diyl)diacetic acid. 2,2′-(naphthalene-2,6-diyl)diacetic acid can be accessed in several ways including, but not limited to, the following:

-   -   (a) a homologation route starting from         naphthalene-2,6-diyldimethanol, followed by activation,         cyanation, and hydrolysis;     -   (b) Pd-mediated cross-coupling using di-tert-butyl malonate and         2,6-dibromonaphthalene, followed by ester hydrolysis and         decarboxylation; or     -   (c) Pd-mediated cross-coupling using         tert-butyl((1-methoxyvinyl)oxy)dimethylsilane and         2,6-halonaphthalene, followed by ester hydrolysis.         The synthesized 2,2′-(naphthalene-2,6-diyl)diacetic acid can,         for example, (a) be coupled to 2 equivalents of naltrexone using         standard coupling reagents (such as         (benzotriazol-1-yloxy)tripyrrolidinophosphonium         hexafluorophosphate (PyBOP), propylphosphonic anhydride (T₃P),         or the like), or (b) first converted to         2,2′-(naphthalene-2,6-diyl)diacetyl chloride using Ghosez's         reagent (1-chloro-N,N,2-trimethyl-1-propenylamine) or SOCl₂         (thionyl chloride), followed by naltrexone addition.

EXAMPLES

The invention is further illustrated by the following examples, which should not be construed as further limiting.

Examples Example 1: Synthesis of Compounds of the Invention 1.1 Compound 1 Synthesis of 1,5-bis(bromomethyl)naphthalene

1,5-Dimethylnaphthalene (1.0 g, 6.4 mmol), N-bromosuccinimide (2.3 g, 12.8 mmol), benzyl peroxide (31 mg, 0.13 mmol) were dissolved in dichloroethane (10 mL). The reaction was heated to reflux and left to stir overnight for 18 hours. The reaction was cooled to room temperature and a solid crashed out of solution, which was filtered and washed with cold ethyl acetate. The solid was re-dissolved in dichloromethane (30 mL) and washed with saturated sodium hydrogen carbonate solution (3×30 mL) and brine (3×30 mL). The organic phase was dried with sodium sulphate, filtered and reduced to dryness under vacuum. The crude solid was then triturated with hot ethyl acetate (10 mL) and filtered. This yielded 1,5-bis(bromomethyl)naphthalene as a white powder (1.22 g, 60%).

¹H NMR (396 MHz, CDCl₃): δ 8.18 (d, 2H), 7.60 (d, 2H), 7.55 (t, 2H), 4.96 (s, 4H).

Synthesis of 2,2′-(naphthalene-1,5-diyl)diacetonitrile

1,5-Bis(bromomethyl)naphthalene (1.2 g, 3.82 mmol), potassium cyanide (746 mg, 11 mmol) and tetrabutylammonium bromide (615 mg, 1.91 mmol) were dissolved in dichloromethane:water (15 mL: 15 mL) and stirred at room temperature for 18 hours. The reaction was quenched with 2 M sodium hydroxide and stirred for 15 minutes. The aqueous phase was extracted with dichloromethane (3×50 mL); the organic phases were combined, dried using sodium sulphate and reduced to dryness under vacuum. The crude product was then filtered through a plug of silica to remove impurities to yield 2,2′-(naphthalene-1,5-diyl)diacetonitrile as a yellow solid (649 mg, 82%).

¹H NMR (396 MHz, CDCl₃): δ 7.92 (d, 2H), 7.69 (d, 2H), 7.61 (d, 2H), 4.18 (s, 4H).

Synthesis of 2,2′-(naphthalene-1,5-diyl)diacetic acid

2,2′-(Naphthalene-1,5-diyl)diacetonitrile (649 mg, 3.15 mmol) was dissolved in sulphuric acid:acetic acid:water (4 mL:4 mL:4 mL) and heated to reflux for 4 hours. The reaction was allowed to cool back down to room temperature and the reaction mixture was diluted with water (30 mL). The aqueous was extracted with 2-methyl tetrahydrofuran, dried with sodium sulphate and reduced to dryness under vacuum. The crude solid obtained was triturated with diethyl ether to yield 2,2′-(naphthalene-1,5-diyl)diacetic acid as a grey solid (636 mg, 83%).

¹H NMR (396 MHz, DMSO-d₆): δ 12.39 (s, 2H), 7.90 (d, 2H), 7.49 (t, 2H), 7.43 (d, 2H), 4.04 (s, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-1,5-diyl)diacetate

To a solution of 2,2′-(naphthalene-1,5-diyl)diacetic acid (1.0 g, 4.09 mmol) in tetrahydrofuran (20 mL) was added triethylamine (1.71 mL, 12.28 mmol), naltrexone (2.80 g, 8.29 mmol) and (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (4.70 g, 9.01 mmol). The reaction mixture was stirred at room temperature overnight. The reaction was therefore quenched with water (70 mL) and extracted with dichloromethane (3×75 mL). The organic phases were combined and washed with saturated sodium bicarbonate solution (3×100 mL), dried using a phase separator and reduced to dryness under vacuum. The crude foam was purified in two batches via reverse phase chromatography (pH 9 ammonium bicarbonate buffer, 30% to 100% acetonitrile). This yielded bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-1,5-diyl)diacetate as a colourless solid after extraction with ethyl acetate from the relevant fractions (1.6 g, 44%).

¹H NMR (396 MHz, DMSO-d₆): δ 7.90-8.10 (m, 2H), 7.47-7.70 (m, 4H), 6.87 (d, 2H), 6.64 (d, 2H), 5.09 (s, 2H), 4.90 (s, 2H), 4.41 (s, 4H), 3.08-3.20 (m, 2H), 2.96-3.08 (m, 2H), 2.75-2.96 (m, 2H), 2.48-2.69 (m, 2H), 2.19-2.41 (m, 5H), 1.99-2.16 (m, 2H), 1.82-1.93 (m, 2H), 1.61-1.82 (m, 2H), 1.32-1.55 (m, 2H), 1.18-1.28 (m, 2H), 0.69-1.01 (m, 2H), 0.43 (d, 4H), 0.11 (d, 4H). [M+H]⁺ 891.40.

1.2 Compound 2 Synthesis of 2,2′-(naphthalene-2,6-diyl)diacetonitrile

To a solution of 1,6-di(hydroxymethyl)naphthylene (3.5 g, 18.6 mmol) in dimethylformamide (70 mL) at 5° C. was added triethylamine (6.5 mL, 46.5 mmol), followed by methanesulfonyl chloride (3.31 mL, 42.8 mmol) over 2 min. The reaction mixture was stirred for 3 hours and then potassium cyanide (3.6 g, 55.8 mmol) was added. The reaction mixture was heated at 50° C. for 4 hours, cooled to room temperature, diluted with ethyl acetate (100 mL) and washed with diluted brine (4×150 mL). The organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was dissolved in dimethylformamide (50 mL) and potassium cyanide (3.6 g, 55.8 mmol) added and the reaction mixture heated at 90° C. for 3 hours. The reaction was cooled, poured into water (500 mL) and extracted with ethyl acetate (2×100 mL). The combined organic layers were washed with water (3×300 mL), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give 2,2′-(naphthalene-2,6-diyl)diacetonitrile (2.95 g, 89% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.85-7.80 (m, 4H), 7.42 (dd, 2H), 3.92 (s, 4H).

Synthesis of 2,2′-(naphthalene-2,6-diyl)diacetic acid

To a mixture of 2,2′-(naphthalene-2,6-diyl)diacetonitrile (2.95 g, 14.3 mmol), water (13 mL) and acetic acid (18 mL) was added sulphuric acid (13 mL). The reaction mixture was heated at reflux for 20 hours, cooled and then poured into water (350 mL) at 5° C. The resulting precipitate was filtered, washed with water and dried under suction for 30 min. The a half of the resulting solid was added to ethyl acetate (50 mL) and the suspension sonicated for 30 min. The resulting solid was collected by filtration and dried to give 2,2′-(naphthalene-2,6-diyl)diacetic acid (0.88 g, 25% yield).

¹H NMR (300 MHz, 1,4-dioxane-d₈): δ 7.74 (d, 2H), 7.70 (s, 2H), 7.40 (d, 2H), 3.71 (s, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-2,6-diyl)diacetate

To a solution of 2,2′-(naphthalene-2,6-diyl)diacetic acid (0.25 g, 1.02 mmol) in tetrahydrofuran (30 mL) was added Ghosez's reagent (328 mg, 2.46 mmol). The reaction mixture as stirred for 90 min and then a mixture of naltrexone (804 mg, 2.35 mmol) and triethylamine (0.43 mL, 3.07 mmol) in tetrahydrofuran (5 mL) was added. The reaction mixture was stirred a further hour and then diluted with ethyl acetate (50 mL) and washed with diluted aqueous solution of sodium hydrogencarbonate (50 mL). The organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica chromatography eluted with a gradient of 1-5% triethylamine in ethyl acetate to give bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-2,6-diyl)diacetate (158 mg, 17% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.83 (d, 4H), 7.51 (dd, 2H), 6.79 (d, 2H), 6.63 (d, 2H), 4.70 (s, 2H), 4.06 (s, 4H), 3.19 (d, 2H), 3.13-2.93 (m, 4H), 2.70 (dd, 2H), 2.59 (dd, 2H), 2.47-2.28 (m, 8H), 2.22 (dt, 2H), 1.88 (dt, 2H), 1.69-1.45 (m, 6H), 0.95-0.80 (m, 2H), 0.61-0.52 (m, 4H), 0.18-0.11 (m, 4H). [M+H]⁺ 891.40.

1.3 Compound 3 Synthesis of 1,5-bis(allyloxy)naphthalene

To a solution of 1,5-dihydroxynaphtalene (10 g, 62 mmol) in acetone (55 mL) and tetrahydrofuran (55 mL) were added potassium carbonate (21 g, 149 mmol) and allyl bromide (13 mL, 149 mmol). The mixture was heated at reflux for 16 hours and diluted with ethyl acetate. The organic layer was washed with 1 M aqueous solution of sodium hydroxide (100 mL), water and brine, dried over magnesium sulfate, filtered and concentrated under reduced pressure to give a brown solid. The solid was triturated with hexane to give 1,5-bis(allyloxy)naphthalene (8.1 g, 54% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.89 (d, 2H), 7.35 (t, 2H), 6.84 (d, 2H), 6.24-6.11 (m, 2H), 5.52 (d, 2H), 5.33 (d, 2H), 4.70 (d, 4H).

Synthesis of 2,6-diallylnaphthalene-1,5-diol

A suspension of 1,5-bis(allyloxy)naphthalene (6.1 g, 25 mmol) in anhydrous dodecane (15 mL) was degassed with argon and heated at 200° C. for 1 hour under an atmosphere of argon. The reaction was cooled down to room temperature and the solid was triturated with hexane, filtered and washed with hexane to give 2,6-diallylnaphthalene-1,5-diol (5.4 g, 88% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.69 (d, 2H), 7.23 (d, 2H), 6.14-6.01 (m, 2H), 5.48 (d, 2H), 5.27-5.21 (m, 4H), 3.58 (d, 4H).

Synthesis of 2,6-diallylnaphthalene-1,5-diyl diacetate

To a solution of 2,6-diallylnaphthalene-1,5-diol (1.0 g, 4.1 mmol) in dichloromethane (25 mL) were added triethylamine (2 mL, 14.5 mmol) and acetic anhydride (1.9 mL, 20.8 mmol). After stirring at room temperature under an atmosphere of argon for 16 hours, the reaction was quenched with water, extracted with dichloromethane (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica chromatography, eluted with 15% ethyl acetate in heptanes to give 2,6-diallylnaphthalene-1,5-diyl diacetate (1.1 g, 84% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.58 (d, 2H), 7.36 (d, 2H), 5.96-5.86 (m, 2H), 5.13-5.08 (m, 4H), 3.41 (d, 4H), 2.45 (s, 6H).

Synthesis of 2,2′-(1,5-diacetoxynaphthalene-2,6-diyl)diacetic acid

A solution of 2,6-diallylnaphthalene-1,5-diyl diacetate (1.1 g, 3.4 mmol) in dichloromethane:methanol (20 mL:20 mL) was ozonolized at −78° C. for 10 minutes, then evaporated a low heat under reduced pressure to dryness to give an orange gum. The residue was stirred in formic acid (15 mL) and aqueous hydrogen peroxide (35%, 8 mL) at room temperature for 16 hours. The reaction was quenched with water, extracted with ethyl acetate (×3), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was triturated with diethyl ether:heptane (1:1) to give 2,2′-(1,5-diacetoxynaphthalene-2,6-diyl)diacetic acid (370 mg, 30% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.69 (d, 2H), 7.52 (d, 2H), 3.67 (s, 4H), 2.46 (s, 6H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-diacetoxynaphthalene-2,6-diyl)diacetate

To a solution of 2,2′-(1,5-diacetoxynaphthalene-2,6-diyl)diacetic acid (200 mg, 0.56 mmol) in dichloromethane (30 mL) and triethylamine (0.31 mL, 2.22 mmol) were added naltrexone (375 mg, 1.11 mmol) and (benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate) (635 mg, 1.22 mmol) and stirred at room temperature under an atmosphere of argon for 3 hours. The reaction was quenched with brine, extracted with dichloromethane (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). The combined fractions were extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give a brown solid. The compound was repurified by silica chromatography, eluted with 50% dichloromethane in ethyl acetate (with 1% triethylamine) to give bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-diacetoxynaphthalene-2,6-diyl)diacetate (170 mg, 30% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.69 (d, 2H), 7.59 (d, 2H), 6.77 (d, 2H), 6.61 (d, 2H), 5.20 (br s, 2H), 4.68 (s, 2H), 3.95 (q, 4H), 3.18 (d, 2H), 3.08-2.97 (m, 4H), 2.67 (dd, 2H), 2.57 (dd, 2H), 2.51 (s, 6H), 2.44-2.35 (m, 6H), 2.31 (dt, 2H), 2.11 (td, 2H), 1.90-1.84 (m, 2H), 1.66-1.56 (m, 4H), 0.90-0.80 (m, 2H), 0.57-0.52 (m, 4H), 0.11-0.15 (m, 4H). [M+H]⁺ 1007.59.

1.4 Compound 4 Synthesis of 2,6-diallyl-1,5-dimethoxynaphthalene

To a solution of 2,6-diallylnaphthalene-1,5-diol (1.0 g, 4.16 mmol) in anhydrous acetone (25 mL) were added potassium carbonate (1.2 g, 9.15 mmol) followed by dimethyl sulfate (0.87 mL, 9.15 mmol) dropwise at room temperature under an atmosphere of argon and stirred at reflux for 16 hours. The reaction was quenched with water, extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The compound was purified by silica chromatography, eluted with 5% ethyl acetate in heptane to give 2,6-diallyl-1,5-dimethoxynaphthalene (915 mg, 83% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.81 (d, 2H), 7.32 (d, 2H), 6.09-5.98 (m, 2H), 5.11-5.07 (m, 4H), 3.90 (s, 6H), 3.58 (d, 4H).

Synthesis of 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetic acid

To a mixture of 2,6-diallyl-1,5-dimethoxynaphthalene (600 mg, 2.23 mmol) in 1,4-dioxane (35 mL) and water (10 mL) were added sodium periodate (3.8 g, 17.8 mmol) and potassium osmate(VI) dehydrate (8.2 mg, 0.022 mmol) and stirred vigorously at room temperature for 16 hours. The reaction was filtered through a pad of celite, rinsed with ethyl acetate, the filtrate was washed with water and the organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure to give a white solid. The residue was stirred in tert-butanol:water (24 mL:15 mL) and 2-methyl-2-butene (18 mL), sodium dihydrogen phosphate (3.7 g, 31.3 mmol) and sodium chlorite (3.6 g, 40.2 mmol) were added. The mixture was stirred vigorously at room temperature for 4 hours and filtered through a pad of celite and rinsed with ethyl acetate and 2-methyltetrahydrofuran. The filtrate was extracted with ethyl acetate (×2) and concentrated under reduced pressure. The residue was partitioned between a 2 M aqueous solution of sodium hydroxide and ethyl acetate and the aqueous layer was extracted with ethyl acetate and diethyl ether. The aqueous layer was acidified with a 2 M aqueous solution of hydrochloric acid and extracted with 2-methyltetrahydrofuran (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was triturated with diethyl ether (×2) to give 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetic acid (170 mg, 25% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.79 (d, 2H), 7.41 (d, 2H), 3.90 (s, 6H), 3.75 (s, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetate

To a solution of 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetic acid (170 mg, 0.56 mmol) in 2-methyltetrahydrofuran (50 mL) and triethylamine (0.31 mL, 2.23 mmol) were added naltrexone (897 mg, 2.62 mmol) and benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (1.5 g, 2.88 mmol) and stirred at room temperature for 16 hours. The reaction was quenched with brine, extracted with ethyl acetate (×2) and dichloromethane, dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). The combined fractions were extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give a yellow solid. The compound was repurified by silica chromatography, eluted with 40% dichloromethane in ethyl acetate (with 1% triethylamine) to give bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetate (179 mg, 33% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.89 (d, 2H), 7.53 (d, 2H), 6.83 (d, 2H), 6.64 (d, 2H), 5.21 (br s, 2H), 4.68 (s, 2H), 4.13 (s, 4H), 4.01 (s, 6H), 3.20-2.95 (m, 6H), 2.70-2.55 (m, 4H), 2.46-2.28 (m, 8H), 2.16-2.08 (m, 2H), 1.90-1.85 (m, 2H), 1.66-1.53 (m, 4H), 0.92-0.82 (m, 2H), 0.57-0.54 (m, 4H), 0.15-0.13 (m, 4H). [M+H]⁺ 951.32.

1.5 Compound 5 Synthesis of 1,5-difluoronaphtalene

To a suspension of 1,5-diaminonaphthalene (5.0 g, 31.6 mmol) in tetrahydrofuran (12 mL) was added slowly fluoroboric acid (50% in water, 140 mL) at −10° C. followed by a solution of sodium nitrite (18 g, 260 mmol) in water (60 mL) over 45 minutes. The mixture was stirred at −10° C. for 1 hour and sodium tetrafluoroborate (35 g, 318 mmol) was added portionwise. The reaction was stirred at room temperature for 1.5 hours. The solid was filtered, rinsed with diethyl ether (500 mL) and dried under vacuum in a dessicator overnight. The solid was suspended in xylenes and heated at reflux for 1 hour. The reaction was concentrated carefully under vacuum and the residue was diluted with dichloromethane and filtered through a pad of celite which was rinsed with dichloromethane and the filtrate was evaporated carefully under reduced pressure. The residue was purified by silica chromatography eluted with 2% ethyl acetate in heptanes followed by reverse phase chromatography (C18). The desired fractions were combined and acetonitrile was evaporated under reduced pressure. The aqueous layer was extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give 1,5-difluoronaphtalene (1.6 g, 32% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.88 (d, 2H), 7.46 (ddd, 2H), 7.21 (ddd, 2H). ¹⁹F NMR (282 MHz, CDCl₃): δ −121.4.

Synthesis of 2,6-dibromo-1,5-difluoronaphtalene

To a solution of 1,5-difluoronaphtalene (877 mg, 5.34 mmol) in anhydrous tetrahydrofuran (90 mL) and anhydrous tetramethylethylenediamine (3.3 mL, 21.3 mmol) was added slowly sec-butyllithium (1.2 M in cyclohexane, 17 mL, 20.4 mmol) at −78° C. under an atmosphere of argon. The solution was stirred at −78° C. for 2 hours and bromine (1.7 mL, 32.0 mmol) was added slowly. The mixture was warmed up slowly to room temperature over 2 hours and quenched with an aqueous solution of ammonium chloride. The mixture was extracted with ethyl acetate (×2) and the combined organic layers were washed with a 10% aqueous solution of sodium thiosulfate, dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). The desired fractions were combined and acetonitrile was evaporated under reduced pressure. The aqueous layer was extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give 2,6-dibromo-1,5-difluoronaphtalene (284 mg, 16% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.75 (d, 2H), 7.64 (dd, 2H).

Synthesis of dimethyl 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetate

To a solution of 2,6-dibromo-1,5-difluoronaphtalene (234 mg, 0.73 mmol) in degassed anhydrous dimethylformamide (4.8 mL) were added tris(dibenzyllideneacetone)dipalladium(0) (208 mg, 0.36 mmol), tributylphosphine (1M in toluene, 0.22 mL, 0.22 mmol) and 1-(tert-butyldimethylsilyloxy)-1-methoxyethene (0.63 mL, 2.90 mmol). The reaction mixture was flushed with argon and irradiated at 120° C. for 1 hour. Further 1-(tert-butyldimethylsilyloxy)-1-methoxyethene (0.31 mL, 1.45 mmol) was added and the mixture was irradiated at 120° C. for 1 hour. The mixture was filtered through a pad of celite and rinsed with ethyl acetate. The filtrate was washed with water (×3), dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). The desired fractions were combined and acetonitrile was evaporated. The aqueous layer was extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure. The compound was purified further by silica chromatography eluted with 30% ethyl acetate in heptanes to give dimethyl 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetate (90 mg, 33% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.83 (d, 2H), 739 (dd, 2H), 3.85 (s, 4H), 3.72 (s, 6H). ¹⁹F NMR (300 MHz, CDCl₃): δ −125.9.

Synthesis of 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetic acid

To a solution of dimethyl 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetate (90 mg, 0.291 mmol) in a mixture of tetrahydrofuran (8 mL) and water (4 mL) was added lithium hydroxide monohydrate (37 mg, 0.881 mmol). After stirring for 4 hours at room temperature, the mixture was diluted with water and washed with diethyl ether. The aqueous layer was acidified with a 2 M aqueous solution of hydrochloric acid and extracted with 2-methyltetrahydrofuran (×3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure to give a solid which was triturated with diethyl ether to afford 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetic acid (62 mg, 76% yield).

¹H NMR (400 MHz, DMSO-d₆): δ 7.78 (d, 2H), 7.53 (dd, 2H), 3.80 (s, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-difluoronaphthalene-2,6-diyl)diacetate

To a suspension of 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetic acid (65 mg, 0.231 mmol) in 2-methyltetrahydrofuran (15 mL) and triethylamine (0.13 mL, 0.924 mmol) were added naltrexone (158 mg, 0.462 mmol) and benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (264 mg, 0.507 mmol). The mixture was stirred at room temperature for 2 hours, quenched with brine and extracted with ethyl acetate (×3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). The combined fractions were extracted with ethyl acetate (×2), dried over magnesium sulfate, filtered and concentrated under reduced pressure to give bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-difluoronaphthalene-2,6-diyl)diacetate (70 mg, 32% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.87 (d, 2H), 7.54 (dd, 2H), 6.82 (d, 2H), 6.64 (d, 2H), 5.19 (br s, 2H), 4.70 (s, 2H), 4.14 (s, 4H), 3.19 (d, 2H), 3.09-2.97 (m, 4H), 2.68 (dd, 2H), 2.59 (dd, 2H), 2.44-2.37 (m, 6H), 2.32 (dt, 2H), 2.10 (td, 2H), 1.90-1.86 (m, 2H), 1.66-1.56 (m, 4H), 0.90-0.81 (m, 2H), 0.57-0.52 (m, 4H), 0.15-0.11 (m, 4H). ¹⁹F NMR (376 MHz, CDCl₃): δ −125.4. [M+H]+ 927.40.

1.6 Compound 6 Synthesis of 1,5-dichloronaphthalene-2,6-diol

To a solution of naphthalene-2,6-diol (3.0 g, 18.7 mmol) in acetic acid (90 mL) was added sulfuryl chloride (3.0 mL, 37.5 mmol) dropwise and the mixture stirred at room temperature for 3 hours. Water (50 mL) was added to the reaction flask and the mixture stirred for 10 minutes. The grey coloured solid which precipitates out of solution was filtered off and washed with water (3×50 mL) and heptane (3×30 mL), notably under an inverted funnel with continuous nitrogen flow over the solid to prevent oxidation. The light grey solid was quickly transferred to a flask and left under vacuum overnight to dry, to afford 1,5-dichloronaphthalene-2,6-diol as a light grey solid (2.65 g, 62% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.95 (d, 2H), 7.34 (d, 2H), 5.79 (s, 2H, OH).

Synthesis of 1,5-dichloronaphthalene-2,6-diyl bis(trifluoromethanesulfonate)

To a suspension of 1,5-dichloronaphthalene-2,6-diol (2.65 g, 11.6 mmol) in dichloromethane (100 mL), cooled in an ice bath, was added pyridine (5.61 mL, 69.4 mmol) to give a brown solution. Using a dropping funnel, trifluoromethanesulfonic anhydride (4.3 mL, 25.4 mmol) was added dropwise over 20 minutes. After completion of the addition, the ice bath was removed and the reaction mixture stirred for 18 hours at room temperature. Water (30 mL) was added to the mixture followed by aq. 2M hydrochloric acid (20 mL) with stirring. The layers were separated and dichloromethane layer washed with aqueous 1 M hydrochloric acid (3×100 mL), water (30 mL) and aqueous sodium hydrogen carbonate (30 mL). The dichloromethane layer was passed through a phase separator and concentrated under reduced pressure to afford a grey solid (3.84 g). The crude solid was re-dissolved in dichloromethane and absorbed onto silica and purified by flash chromatography (C18 cartridge) eluting with dichloromethane to afford 1,5-dichloronaphthalene-2,6-diyl bis(trifluoromethanesulfonate) as a white solid (2.0 g, 35% yield).

¹H NMR (400 MHz, CDCl₃): δ 8.39 (d, 2H), 7.66 (d, 2H). ¹⁹F NMR (372 MHz, CDCl₃): δ −73.11 (s).

Synthesis of dimethyl 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetate

To a solution of 1,5-dichloronaphthalene-2,6-diyl bis(trifluoromethanesulfonate) (1.99 g, 4.03 mmol) in 1,4-dioxane (degassed by vacuum/nitrogen purge×3), was added lithium acetate (1.06 g, 16.1 mmol), tetrakis(triphenylphosphine)palladium(0) (466 mg, 0.40 mmol) and 1-(tert-butyldimethylsilyloxy)-1-methoxyethene (3.04 g, 16.1 mmol) and the mixture heated at 100° C. for 18 hours. The reaction mixture was cooled and diluted with water (100 mL) followed by extraction with tert-butylmethyl ether (3×30 mL). The organic layer was washed with water (30 mL) and aqueous ammonium chloride (30 mL), dried (magnesium sulfate), filtered then absorbed onto silica and purified by flash column chromatography eluting with 10% ethylacetate in heptane to afford dimethyl 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetate as a white solid (422 mg, 31% yield).

¹H NMR (400 MHz, CDCl₃): δ 8.23 (d, 2H), 7.49 (d, 2H), 3.99 (s, 4H), 3.70 (s, 6H).

Synthesis of 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetic

To a solution of dimethyl 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetate (420 mg, 1.23 mmol) in tetrahydrofuran (30 mL) and methanol (4 mL) was added aq. 2 M sodium hydroxide (4 mL, 8 mmol) and stirred at room temperature overnight. The solvent was evaporated under reduced pressure to give a residue which was dissolved in water (30 mL). Additional aqueous 2 M sodium hydroxide (2 mL) was added and the aqueous layer washed with tert-butylmethyl ether (20 mL). The aqueous layer was carefully acidified with stirring using aq. 2M hydrochloric acid. The white solid formed was filtered off and washed with water, triturated with tert-butylmethyl ether and air dried to afford 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetic acid as a white solid (305 mg, 79% yield).

¹H NMR (400 MHz, DMSO-d₆): δ 12.66 (br.s, 2H), 8.20 (d, 2H), 7.72 (d, 2H), 3.98 (s, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetate

To a suspension of 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetic acid (150 mg, 0.48 mmol) in dry tetrahydrofuran (15 mL) under nitrogen, was added naltrexone (327 mg, 0.96 mmol), triethylamine (0.20 mL, 1.44 mmol) and (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (548 mg, 1.05 mmol) and the mixture was stirred at room temperature for 4 hours. The solvent was removed and the green residue re-dissolved in ethylacetate (20 mL) and washed with water (20 mL), aqueous ammonium chloride (3×20 mL), dried (magnesium sulfate), filtered and concentrated under reduced pressure to give a crude solid. The solid was triturated with tert-butylmethyl ether followed with further purification by reverse phase chromatography (C18 cartridge), eluting with a gradient of 20-90% acetonitrile in 0.1% aq. ammonium formate buffer. The appropriate fractions were combined and partially concentrated under reduced pressure and extracted with ethylacetate (3×30 mL). The organic layer was washed with aqueous ammonium chloride (30 mL). The aqueous layer was re-extracted with dichloromethane (2×30 mL) and washed with aqueous ammonium chloride. Both organic layers were combined, dried (magnesium sulfate), filtered, and concentrated under reduced pressure. The product was co-evaporated with acetonitrile, to remove traces of solvent, to afford bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dichloronaphthalene-2,6-diyl)diacetate as a white solid (182 mg, 40% yield).

¹H NMR (400 MHz, CDCl₃): δ 8.28 (d, 2H), 7.66 (d, 2H), 6.83 (d, 2H), 6.65 (d, 2H), 4.70 (s, 2H), 4.27 (s, 4H), 3.19 (br. s, 2H), 3.04 (d, 2H), 2.98 (dt, 2H), 2.67 (br. d, 2H), 2.61 (dd, 2H), 2.33 (overlapped m, 8H), 2.11 (dt, 2H), 1.89 (dt, 2H), 1.58 (overlapped m, 4H), 0.85 (m, 2H), 0.54 (d, 4H), 0.14 (d, 4H). [M³⁵Cl/³⁷Cl]⁺ 959.02/961.11.

1.7 Compound 7 Synthesis of 1,5-dibromo-2,6-bis(methoxymethoxy)naphthalene

To a solution of 1,5-dibromonaphthalene-2,6-diol (5.0 g, 15.73 mmol) in dichloromethane (100 mL) was added diisopropylethylamine (16.43 mL) and the reaction was cooled at 0° C. in water/ice bath. To the reaction mixture was added chloromethyl methyl ether (7.17 mL) via a syringe and dropwise over 5 minutes. The reaction was left to stir for 18 hours. After this time the reaction was diluted with water (100 mL) and dichloromethane (100 mL). The organic was separated and the aqueous re-extracted with dichloromethane (100 mL). The combined organics were washed with brine (150 mL), filtered through a phase separator and reduced to dryness to give brown gum. The gum was triturated with heptane to give a pale brown solid which was filtered to give 1,5-dibromo-2,6-bis(methoxymethoxy)naphthalene as yellow solid (5.79, 91%).

¹H NMR (396 MHz, DMSO-d₆): δ 8.12 (d, 2H), 7.63 (d, 2H), 5.38 (s, 4H), 3.42 (s, 6H).

Synthesis of 2,6-bis(methoxymethoxy)-1,5-dimethylnaphthalene

To a solution of 1,5-dibromo-2,6-bis(methoxymethoxy)naphthalene (1.50 g, 3.69 mmol) in dioxane (75 mL) was added potassium carbonate (1.53 mg, 11.08 mmol) and trimethylboroxine (2.78 g, 22.16 mmol). The mixture was degassed (cycle vacuum-nitrogen ×3) and then palladium-tetrakis(triphenylphosphine) (213 mg, 0.185 mmol) was added before degassing again with vacuum-nitrogen cycles three time. The reaction was heated at reflux 18 hours. The reaction was cooled to room temperature, diluted with sodium hydrogen carbonate (150 mL) and extracted with ethylacetate (100 mL×3). The combined organics were washed with brine (150 mL), dried over sodium sulfate, filtered and reduced to dryness to give a brown solid (1.319 g). The crude was absorbed onto silica and purified by silica column chromatography (dichloromethane:heptane=1:1 to 7:3). The correct fractions were collected and reduced to dryness to give 2,6-bis(methoxymethoxy)-1,5-dimethylnaphthalene as colourless solid (800 mg, 78%).

¹H NMR (396 MHz, CDCl₃): δ 7.80 (d, 2H), 7.38 (d, 2H), 5.25 (s, 4H), 3.53 (s, 6H), 2.56 (s, 6H).

Synthesis 1,5-dimethylnaphthalene-2,6-diol

2,6-Bis(methoxymethoxy)-1,5-dimethylnaphthalene (581 mg, 2.10 mmol) was dissolved in hydrochloric acid 4.0 M dioxane (30 mL) and the reaction stirred at room temperature for 3 hours, the formation of some precipitate was observed. After completion the reaction was reduced to dryness to give 1,5-dimethylnaphthalene-2,6-diol as pale yellow solid (472 mg, quantitative).

¹H NMR (396 MHz, DMSO-d₆): δ 9.06 (s, 2H), 7.57 (d, 2H), 7.10 (d, 2H), 2.36 (s, 6H).

Synthesis 1,5-dimethylnaphthalene-2,6-diyl bis(trifluoromethanesulfonate)

1,5-Dimethylnaphthalene-2,6-diol (395 mg, 2.10 mmol, expected amount, amount from hydrolysis 490 mg) was suspended in dichloromethane (25 mL). Dry triethylamine (637 mg, 6.30 mmol, 0.88 mL) was added at 0° C. Triflic anhydride (1.48 g, 5.25 mmol, 0.88 mL) was added over 10 minutes and the reaction stirred for 5 min and then checked by LC. Dry triethylamine (319 mg, 3.15 mmol, 0.44 mL) was added at 0° C. Triflic anhydride (740 mg, 2.62 mmol, 0.44 mL) was added and the reaction stirred for 5 min and then checked by LC The reaction was quenched by addition of water (70 mL) and diluted with dichloromethane (30 mL). The organic was separated and the aqueous was extracted with dichloromethane (60 mL×2). The combined organics were washed with brine (60 mL), filtered through a phase separator and reduced to dryness to give a brown solid. The crude was absorbed onto silica and purified by silica column chromatography (dichloromethane:heptane=4:6). The correct fractions were collected and reduced to dryness to give the title compound as colourless solid (730 mg, 76%).

¹H NMR (396 MHz, CDCl₃): δ 8.02 (d, 2H), 7.50 (d, 2H), 2.72 (s, 6H). ¹⁹F NMR (372 MHz, CDCl₃): δ −73.47.

Synthesis of dimethyl 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetate

To a solution of 1,5-dimethylnaphthalene-2,6-diyl bis(trifluoromethanesulfonate) (730 mg, 1.61 mmol) in dioxane (18 mL) was added lithium acetate (639 g, 9.68 mmol), tert-butyl((1-methoxyvinyl)oxy)dimethylsilane (1.82 g, 9.68 mmol) and palladium-tetrakis(triphenylphosphine) (186 mg, 0.161 mmol). The mixture was degassed (cycle vacuum-nitrogen×3) and then heated at reflux for 3 hours. The reaction was allowed to cool to room temperature, water (200 mL) was added and the aqueous extracted with ethylacetate (3×60 mL). The combined organics were washed with brine (150 mL), dried over magnesium sulfate, filtered and reduced to dryness to give a black solid. The crude was absorbed onto silica and purified by silica column chromatography (dichloromethane). The correct fractions were collected and reduced to dryness to give dimethyl 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetate as a colourless solid (299 mg, 62%).

¹H NMR (396 MHz, CDCl₃): δ 7.92 (d, 2H), 7.37 (d, 2H), 3.86 (s, 4H), 3.68 (s, 6H), 2.63 (s, 6H).

Synthesis of 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetic acid

To a solution of dimethyl 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetate (299 mg, 0.995 mmol) in tetrahydrofuran:methanol (1:1, 50 mL) was added 1.0 M lithium hydroxide (95.3 mg, 3.98 mmol) and the reaction stirred at room temperature for 18 hours. Lithium hydroxide 1.0 M (95.3 mg, 3.98 mmol) was added and the reaction stirred for 4 hours. The reaction was reduced to dryness, 2-methyltetrahydrofuran (30 mL) was added and the reaction acidified by addition of hydrochloric acid 2.0 M (15 mL) and then water (15 mL). The organic was separated and the aqueous was re-extracted with 2-methyl tetrahydrofuran (50 mL). The combined organics were dried over sodium sulfate, filtered and reduced to dryness to give 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetic acid as a pale cream solid (300 mg, quantitative).

¹H NMR (396 MHz, DMSO-d₆): δ 12.28 (s, 2H), 7.85 (d, 2H), 7.34 (d, 2H), 3.77 (s, 4H), 2.50 (s, 6H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetate

To a suspension of 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetic acid (231 mg, 0.848 mmol) in tetrahydrofuran (dry, 25 mL) was added triethylamine (343 mg, 3.39 mmol, 0.473 mL) and naltrexone (579 mg, 1.70 mmol). To the mixture was then added (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (106 mg, 2.04 mmol) and the reaction left to stir at room temperature for 15 minutes. The reaction was quenched with water (80 mL) and extracted with ethylacetate (3×80 mL). The combined organics were washed with brine (100 mL), dried over sodium sulfate, filtered and reduced to dryness. The crude was purified on reverse phase using water/acetonitrile+ammonium carbonate pH 9 buffer, 30% acetonitrile to 100%. The correct fractions were combined, extracted with ethyl acetate and washed with brine (150 mL), dried over sodium sulfate, filtered, and reduced to dryness to give bis((4R,4aS,7aR,12b S)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(1,5-dimethylnaphthalene-2,6-diyl)diacetate as a colourless foam after co-evaporation with dichloromethane (488 mg, 63%).

¹H NMR (396 MHz, DMSO-d₆): δ 7.98 (d, 2H), 7.52 (d, 2H), 6.82 (d, 2H), 6.71 (d, 2H), 5.14 (s, 2H), 4.93 (s, 2H), 4.21 (s, 4H), 3.16 (d, 2H), 3.06 (d, 2H), 2.91 (td, 2H), 2.72-2.52 (m, 10H), 2.44-2.27 (m, 6H), 2.15-2.05 (m, 2H), 1.93 (td, 2H), 1.78 (ddd, 2H), 1.44 (td, 2H), 1.32-1.21 (m, 2H), 0.93-0.79 (m, 2H), 0.54-0.39 (m, 4H), 0.11 (m, 4H). [M+H]+ 919.40.

1.8 Compound 8 Synthesis of dimethyl 3,3′-(naphthalene-2,6-diyl)(2E,2′E)-diacrylate

To a solution of 2,6-dibromonaphthalene (1.0 g, 3.49 mmol) in degassed dioxane (16 mL) was added methyl acrylate (6.3 mL, 69.9 mmol) followed by N,N-dicyclohexylmethylamine (3.3 mL, 15.4 mmol) and bis(tri-tert-butylphosphine)palladium(0) (71 mg, 0.13 mmol). The reaction mixture was heated at 90° C. for 16 hours then cooled to room temperature, concentrated under reduced pressure and diluted with dichloromethane. The organic layer was washed with 0.5 M aqueous solution of hydrochloric acid (×2), saturated aqueous solution of sodium hydrogen carbonate and brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. The resulting yellow solid was triturated with ethyl acetate followed by water. The solid was then washed with heptane and diethyl ether to give dimethyl 3,3′-(naphthalene-2,6-diyl)(2E,2′E)-diacrylate as a white solid (376 mg, 36% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.91-7.81 (m, 6H), 7.69 (d, 2H), 6.57 (d, 2H), 3.84 (s, 6H).

Synthesis of dimethyl 3,3′-(naphthalene-2,6-diyl)dipropionate

To a mixture of dimethyl 3,3′-(naphthalene-2,6-diyl)(2E,2′E)-diacrylate (370 mg, 1.25 mmol) and 10% palladium on carbon (80 mg) under an atmosphere of argon was added methanol (12 mL) and tetrahydrofuran (4 mL). The reaction mixture was stirred under a hydrogen atmosphere at room temperature for 18 hours. The reaction mixture was filtered through a pad of celite and rinsed with tetrahydrofuran and dichloromethane. The filtrate was concentrated under reduced pressure to give dimethyl 3,3′-(naphthalene-2,6-diyl)dipropionate as a white solid (308 mg, 82%).

¹H NMR (300 MHz, CDCl₃): δ 7.71 (d, 2H), 7.60 (s, 2H), 7.31 (dd, 2H), 3.67 (s, 6H), 3.10 (t, 4H), 2.71 (t, 4H).

Synthesis of 3,3′-(naphthalene-2,6-diyl)dipropionic acid

To a suspension of dimethyl 3,3′-(naphthalene-2,6-diyl)dipropionate (300 mg, 1.0 mmol) in tetrahydrofuran (4 mL), methanol (2 mL) and water (2 mL) was added lithium hydroxide monohydrate (350 mg, 8.0 mmol). The reaction mixture was stirred at room temperature for 3 hours. Tetrahydrofuran and methanol were removed under reduced pressure; the mixture was then diluted with water and cooled to 5° C. before acidifying with 2 M aqueous solution of hydrochloric acid. The resulting solid was filtered, washed with water, heptane, acetonitrile and diethyl ether and dried to give 3,3′-(naphthalene-2,6-diyl)dipropionic acid as a white solid (172 mg, 63% yield).

¹H NMR (300 MHz, DMSO-d₆): δ 7.72 (d, 2H), 7.64 (s, 2H), 7.34 (d, 2H), 3.94 (t, 4H), 2.59 (t, 4H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 3,3′-(naphthalene-2,6-diyl)dipropionate

To a suspension of 3,3′-(naphthalene-2,6-diyl)dipropionic acid (170 mg, 0.62 mmol) in anhydrous tetrahydrofuran (8 mL), was added triethylamine (0.35 mL, 2.49 mmol), naltrexone (469 mg, 1.37 mmol) and (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (779 mg, 1.50 mmol). The reaction mixture was stirred at room temperature for 1 hour and then diluted with ethyl acetate and washed with saturated aqueous solution of sodium hydrogencarbonate and brine. The organic layer was dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). Selected fractions were partitioned between ethyl acetate and brine. The layers were separated, aqueous layer was extracted with ethyl acetate (×2), dried over sodium sulfate, filtered and concentrated under reduced pressure to give bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 3,3′-(naphthalene-2,6-diyl)dipropionate as a white solid (240 mg, 42% yield).

¹H NMR (300 MHz, CDCl₃): δ 7.75 (d, 2H), 7.68 (s, 2H), 7.38 (dd, 2H), 6.74 (d, 2H), 6.64 (d, 2H), 5.21 (br. s, 2H), 4.70 (s, 2H), 3.25-3.19 (m, 6H), 3.11-2.92 (m, 8H), 2.70 (dd, 2H), 2.60 (dd, 2H), 2.48-2.29 (m, 8H), 2.14 (td, 2H), 1.92-1.85 (m, 2H), 1.69-1.58 (m, 4H), 0.91-0.81 (m, 2H), 0.59-0.53 (m, 4H), 0.15 (q, 4H). [M+H]+ 919.39.

1.9 Compound 9 Synthesis of di-tert-butyl 2,2′-(naphthalene-1,8-diyl)diacetate

To tris(dibenzylideneacetone)dipalladium(0) (160 mg, 0.17 mmol) in N,N-dimethylformamide (20 mL) was added a solution of tri-tert-butylphosphine (0.35 mL, 0.35 mmol, 1M in toluene) and degassed by vacuum/nitrogen purge ×3. To this red/brown solution was added ((1-(tert-butoxy)vinyl)oxy)(tert-butyl)dimethyl silane (2.42 g, 10.5 mmol), 1,8-dibromonaphthalene (1.0 g, 3.5 mmol) and zinc fluoride (181 mg, 1.75 mmol). The mixture was heated at 110° C. for 18 hours. Starting material was still present (ca. 39%) so additional tris(dibenzylideneacetone)dipalladium(0) (90 mg, 0.10 mmol), ((1-(tert-butoxy)vinyl)oxy)(tert-butyl)dimethylsilane (2.42 g, 10.5 mmol) and zinc fluoride (181 mg, 1.75 mmol) was added. The mixture was heated at 110° C. for a further 18 hours then the reaction mixture was cooled and poured onto aqueous ammonium chloride (150 mL) and product extracted with tert-butylmethyl ether (2×60 mL). Notably the emulsion required addition of Dicalite filter aid followed by filtration to remove inorganic impurities. The combined organic layer was washed with water (60 mL) and aqueous ammonium chloride (60 mL) and dried (magnesium sulfate). Solvent was removed under reduced pressure to afford a crude red/brown oil (3.5 g). The crude material was absorbed onto silica and purified by flash column chromatography eluting with 0-5% tert-butylmethyl ether-heptane to afford di-tert-butyl 2,2′-(naphthalene-1,8-diyl)diacetate as a yellow solid (303 mg, 24% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.77 (d, 2H), 7.31-7.38 (m, 4H), 4.08 (s, 4H), 1.43 (s, 18H).

Synthesis of 2,2′-(naphthalene-1,8-diyl)diacetyl chloride

Into a capped vessel, di-tert-butyl 2,2′-(naphthalene-1,8-diyl)diacetate (231 mg, 0.65 mmol) was dissolved in thionyl chloride (3 mL). Water (23 mg, 23 μL, 1.29 mmol) was added and the vessel immediately capped and sealed. The mixture was stirred at room temperature for 18 hours. The cap was removed (some pressure observed) the contents were transferred to a round-bottom flask and solvent was removed by co-evaporation with dichloromethane three times, under reduced pressure to afford a red/brown colored residue (504 mg). The crude was dissolved in dichloromethane and passed through a short pad of silica eluting with dichloromethane. The solvent was removed under reduced pressure to afford 2,2′-(naphthalene-1,8-diyl)diacetyl chloride (365 mg) which was used directly in the next step.

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-1,8-diyl)diacetate

To a solution of 2,2′-(naphthalene-1,8-diyl)diacetyl chloride (365 mg, 0.65 mmol) in dry dichloromethane (10 mL) was added naltrexone (444 mg, 1.3 mmol) and stirred at room temperature for 3.5 hours. To the suspension was added triethylamine (0.27 mL, 1.95 mmol) followed by water (5 mL) and aqueous ammonium chloride (10 mL). The dichloromethane layer was passed through a phase separator and the solvent removed under reduced pressure to afford a crude brown solid. It was re-dissolved in dichloromethane, absorbed onto silica and purified by flash column chromatography eluting with 50-100% ethylacetate in heptane. The desired fraction were concentrated to dryness and the solid was further re-crystallized from ethylacetate/tert-butylmethyl ether and heptane to afford bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-1,8-diyl)diacetate as a white solid (150 mg, 26%).

¹H NMR (400 MHz, DMSO-d₆): δ 7.96 (d, 2H), 7.61 (d, 2H), 7.52 (t, 2H), 6.83 (d, 2H), 6.72 (d, 2H), 5.14 (s, 2H), 4.94 (s, 2H), 4.62 (q, 4H), 3.16 (d, 2H), 3.07 (d, 2H), 2.91 (dt, 2H), 2.62 (m, 4H), 2.36 (m, 6H), 2.12 (br.d, 2H), 1.92 (br.t, 2H), 1.77 (br.d, 2H), 1.44 (t, 2H), 1.24 (br.d, 2H), 0.86 (m, 2H), 0.49 (d, 4H), 0.13 (d, 4H). [M+H]⁺ 891.40.

1.10 Compound 10 Synthesis of di-tert-butyl 2,2′-(naphthalene-2,7-diyl)diacetate

To a suspension of 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium chloride (8.5 mg, 0.02 mmol), palladium(0) bis(dibenzylideneacetone)₂ (12 mg, 0.02 mmol) and lithium bis(trimethylsilyl)amide (4.6 mL, 1 M sol. in toluene, 4.6 mmol) were added sequentially 2,7-dibromonaphthalene (0.29 g, 1.0 mmol) and tert-butylacetate (0.30 mL, 2.2 mmol). The reaction mixture was stirred at room temperature for 3 days, and then was reduced to dryness in vacuo. The crude material was purified by normal phase chromatography (10% ethylacetate in heptane) to give the desired compound di-tert-butyl 2,2′-(naphthalene-2,7-diyl)diacetate as off white solid (160 mg, 45% yield).

¹H NMR (400 MHz, DMSO-d₆): δ 7.84 (d, 2H), 7.71 (s, 2H), 7.37 (d, 2H), 3.72 (s, 4H), 1.40 (s, 18H).

Synthesis of bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-2,7-diyl)diacetate

A solution of di-tert-butyl 2,2′-(naphthalene-2,7-diyl)diacetate (100 mg, 0.28 mmol) and water (0.01 mL, 0.56 mmol) in thionyl chloride (0.81 mL) was stirred overnight in a sealed vial. The reaction mixture was reduced to dryness in vacuum to give the di-acid chloride as a brown solid (acid chloride was used in the next step without further purification). To a solution of naltrexone (0.20 g, 0.59 mmol) and triethylamine (0.1 mL, 0.70 mmol) in dichloromethane (4 mL) was added a solution of the di-acid chloride (prepared above) (75 mg, 0.27 mmol) in dichloromethane (2 mL) dropwise over 5 min. The resulting brown mixture was stirred overnight under an atmosphere of nitrogen. The reaction mixture was concentrated in vacuo and the crude material was purified by normal phase chromatography (SiO₂, eluting 10% acetone in dichloromethane (1% triethylamine) to give the desired compound bis((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl) 2,2′-(naphthalene-2,7-diyl)diacetate as off-white solid (75 mg, 34% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.84 (s, 2H), 7.82 (d, 2H), 7.51 (d, 2H), 6.78 (d, 2H), 6.43 (d, 2H), 4.71 (s, 2H), 4.07 (s, 4H), 3.21 (d, 2H), 3.07 (d, 2H), 3.02 (td, 2H), 2.70 (dd, 2H), 2.68 (dd, 2H), 2.48-2.28 (m, 8H), 2.12 (td, 2H), 1.94-1.83 (m, 2H), 1.69-1.55 (m, 4H), 0.92-0.79 (m, 2H), 0.60-0.51 (m, 4H), 0.17-0.09 (m, 4H). [M+H]⁺ 891.40.

1.11 Compound 2i Synthesis of 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)naphthalen-2-yl)acetic acid

To a solution of 2,2′-(naphthalene-2,6-diyl)diacetic acid (2 g, 8.19 mmol) in tetrahydrofuran (140 mL) was added triethylamine (2.3 mL, 16.38 mmol), benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (5.11 g, 9.82 mmol) and naltrexone (2.79 g, 8.19 mmol). The reaction mixture was stirred at ambient temperature for 16 hours then concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C₁₈). The material obtained was triturated with diethyl ether (×2) to give 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)naphthalen-2-yl)acetic acid (1.01 g, 22%).

¹H NMR (300 MHz, CDCl₃): δ 7.80-7.71 (m, 4H), 7.46 (dd, 1H), 7.42 (dd, 1H), 6.76 (d, 1H), 6.59 (d, 1H), 5.97 (br s, 2H), 4.66 (s, 1H), 4.03 (s, 2H), 3.76 (s, 2H), 3.27 (d, 1H), 3.07-2.99 (m, 2H), 2.78 (dd, 1H), 2.66-2.40 (m, 4H), 2.27 (dt, 1H), 2.10 (td, 1H), 1.92-1.84 (m, 1H), 1.62-1.49 (m, 2H), 0.91-0.79 (m, 1H), 0.55-0.48 (m, 2H), 0.12 (q, 2H). [M+H]⁺ 568.33.

1.12 Compound 4i Synthesis of 2-(6-(2-(tert-butoxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetic acid

To a suspension of 2,2′-(1,5-dimethoxynaphthalene-2,6-diyl)diacetic acid (277 mg, 0.91 mmol) in tert-butyl alcohol (40 mL) and tetrahydrofuran (40 mL) was added 4-dimethylaminopyridine (55 mg, 0.45 mmol), then a solution of di-tert-butyl dicarbonate (190 mg, 0.87 mmol) in tetrahydrofuran (0.5 mL). The reaction mixture was heated at 75° C. overnight then cooled to room temperature and quenched with a saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The organic layers were dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C₁₈) to give 2-(6-(2-(tert-butoxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetic acid (25 mg, 7% yield) as a white solid.

¹H NMR (300 MHz, CDCl₃): δ 7.85 (dd, 2H), 7.40 (dd, 2H), 3.96 (s, 3H), 3.93 (s, 3H), 3.89 (s, 2H), 3.74 (s, 2H), 1.47 (s, 9H).

Synthesis tert-butyl 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetate

To a solution of 2-(6-(2-(tert-butoxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetic acid (25 mg, 0.069 mmol) and triethylamine (0.03 mL, 0.207 mmol) in tetrahydrofuran (5 mL) was added naltrexone (23 mg, 0.069 mmol) followed by (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (40 mg, 0.076 mmol). The reaction mixture was stirred at room temperature under an atmosphere of argon for 4 hours. The reaction mixture was quenched with brine and a saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). Appropriate fractions were combined and concentrated under reduced pressure then extracted with ethyl acetate, dried over magnesium sulfate, filtered and concentrated under reduced pressure to give tert-butyl 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetate (30 mg, 63% yield) as a white solid. [M+H]⁺ 684.91.

Synthesis of 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetic acid

tert-Butyl 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetate (30 mg, 0.044 mmol) and trifluoroacetic acid (0.4 mL) in dichloromethane (1 mL) were stirred at room temperature for 4 hours. The reaction mixture was then concentrated under reduced pressure. The residue was purified by reverse phase chromatography (C18). Appropriate fractions were combined and organic solvent was concentrated under reduced pressure then freeze dried to give 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a, 5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-dimethoxynaphthalen-2-yl)acetic acid (23 mg, 83% yield) as a white solid.

¹H NMR (300 MHz, DMSO-d₆): δ 7.78 (dd, 2H), 7.52 (d, 1H), 7.43 (d, 1H), 6.83 (d, 1H), 6.69 (d, 1H), 4.89 (s, 1H), 4.10 (s, 2H), 3.90 (s, 3H), 3.82 (s, 3H), 3.73 (s, 2H), 3.18-2.97 (m, 2H), 2.88 (td, 1H), 2.72-2.50 (m, 3H), 2.44-2.25 (m, 3H), 2.13-2.01 (m, 1H), 1.98-1.85 (m, 1H), 1.81-1.69 (m, 1H), 1.50-1.33 (m, 1H), 1.31-1.17 (m, 1H), 0.82-0.76 (m, 1H), 0.46 (d, 2H), 0.10 (d, 2H). [M+H]⁺ 628.26.

1.13 Compound 5i Synthesis of 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-difluoronaphthalen-2-yl)acetic acid

To a suspension of 2,2′-(1,5-difluoronaphtalene-2,6-diyl)diacetic acid (200 mg, 0.71 mmol) in anhydrous tetrahydrofuran (25 mL) were added triethylamine (0.20 mL, 1.42 mmol), benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (445 mg, 0.86 mmol) and naltrexone (243 mg, 0.71 mmol) and the reaction mixture was stirred at room temperature under an atmosphere of argon for 16 hours. The reaction was concentrated and purified by reverse phase chromatography (C18). The desired fractions were combined and freeze dried as quickly as possible to give a white solid. This was dissolved in a minimum of dichloromethane and triturated in diethyl ether:heptanes (1:1) to afford 2-(6-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)-1,5-difluoronaphthalen-2-yl)acetic acid (100 mg, 23% yield).

¹H NMR (400 MHz, CDCl₃): δ 7.83 (dd, 2H), 7.53 (dd, 1H), 7.40 (dd, 1H), 6.82 (d, 1H), 6.64 (d, 1H), 4.70 (s, 1H), 4.12 (s, 2H), 3.86 (s, 2H), 3.30 (d, 1H), 3.15-2.98 (m, 3H), 2.76 (dd, 1H), 2.62 (dd, 1H), 2.50-2.41 (m, 3H), 2.29 (dt, 1H), 2.12 (td, 1H), 1.92-1.86 (m, 1H), 1.63-1.54 (m, 2H), 0.92-0.84 (m, 1H), 0.56 (q, 2H), 0.14 (q, 2H). [M+H]+ 604.16.

1.14 Compound 1i Synthesis of 2-(5-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)naphthalen-1-yl)acetic acid

To a suspension of 2,2′-(naphthalene-1,5-diyl)diacetic acid (350 mg, 1.43 mmol) in tetrahydrofuran (36 mL) was added triethylamine (0.2 mL, 1.43 mmol), benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate (744 mg, 1.43 mmol) and then naltrexone (489 mg, 1.43 mmol). The resulting brown mixture was stirred at room temperature. After 18 hours the reaction mixture was concentrated and purified by reverse phase chromatography (C18) twice. Clean fractions were combined and freeze-dried to give 2-(5-(2-(((4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-9-yl)oxy)-2-oxoethyl)naphthalen-1-yl)acetic acid as a white solid (120 mg, 15%).

¹H NMR (400 MHz, DMSO-d₆): δ 7.97-7.90 (m, 2H), 7.56 (d, 1H), 7.53-7.47 (m, 2H), 7.43 (d, 1H), 6.79 (d, 1H), 6.67 (d, 1H), 4.90 (s, 1H), 4.41 (s, 2H), 4.01 (s, 2H), 3.13 (d, 1H), 3.02 (d, 1H), 2.88 (td, 1H), 2.64-2.49 (m, 2H), 2.38-2.29 (m, 3H), 2.10 (td, 1H), 1.90 (dt, 1H), 1.79-1.73 (m, 1H), 1.41 (dt, 1H), 1.23 (dd, 1H), 0.88-0.80 (m, 1H), 0.49-0.40 (m, 2H), 0.13-0.05 (m, 2H) (COOH and OH protons are not observed, contains 3.4% w/w of ammonium formate). [M+H]⁺ 568.29.

Example 2: Whole Blood Stability Assay

Naltrexone prodrug stability was assessed using freshly collected whole blood (within 24-hr collection) from pooled human (n=3) donors. The incubation mixtures were prepared by spiking the prodrugs into pre-warmed (37 degrees C.) fresh whole blood to a final concentration of 50 nM. After gentle mixing, aliquots of incubation mixtures were immediately transferred into four different 96-deep well plates. One plate was used for each time point. The plates were incubated at 37 degrees C. at a shaking speed of 100 rpm. At time points 15, 30, 60 and 120 minutes, the reaction was quenched by addition of a mixture of water and acetonitrile containing the internal standard (naltrexone-D₃). Time point 0 minutes was prepared separately by spiking the prodrugs into a quenched whole blood to obtain a final concentration of 50 nM. All samples were vortexed at a low speed for 15 min and centrifuged at 3900 rpm for 15 min. Supernatants were transferred into 96-well plates for LC-MS/MS analysis to monitor the depletion of the prodrugs and the formation of naltrexone.

The amount of remaining prodrug and released naltrexone for each sample was quantitated against the calibration curves prepared with the whole blood. The human whole blood was purchased from BioreclamationIVT (Westbury, N.Y., USA). Naltrexone-D₃ was purchased from CERILLIANT® (Round Rock, Tex., USA). Table C shows the half-life of the prodrugs and the amount of naltrexone (in equivalents) measured in whole blood at the 2 hour timepoint. Where multiple runs have been completed, average values are reported.

TABLE C t_(1/2) at 37 degrees Naltrexone formed C. in human whole in human whole blood Prodrug blood (min) at 2 hours (equiv.) Compound 1 26.4 1.18 Compound 2 20.9 1.58 Compound 3 14.8 1.24 Compound 4 28.9 1.44 Compound 5 20.4 1.35 Compound 6 25.7 0.99 Compound 7 58.6 0.88 Compound 8 26.3 1.18 Compound 9 40.9 1.43 Compound 10 14.7 1.60 Reference 54.7 0.78 Compound A

Reference Compound A is disclosed in Burce et al., Journal of Chromatography, 137 (1977), 323-332 as NTX-3-terephthaloyl-NTX.

Example 3: Pharmacokinetic Evaluation of the Release of Naltrexone from Compound 2 in Rats Following a Single Intramuscular Injection

Five male Sprague-Dawley rats were allowed to acclimate to the test facility for at least 2 days prior to study start. For dose administration of Compound 2, the rats were lightly anesthetized with isofluorane, the hind leg shaved and dosed intramuscularly with the formulation using a 21G needle. All animals were observed at dosing and each scheduled collection. Serial whole blood samples were collected via sublingual route (˜150 μL) at 1, 8, and 24 hours post dose, and at 2, 4, 7, 10, 14, 17, 21, 24, 28, 35, 42, 49, 56, 63, 71, 78, 85, and 91 days post dose.

Blood samples were placed into K₂EDTA blood collection tubes. After collection, blood samples were maintained chilled (on wet ice) and centrifuged (11,500 rpm for 2 minutes at 5 degrees C.) within 30 minutes to obtain plasma. Plasma was transferred into a single vial, 1.5 mL screw cap micro-centrifuge tube with inserts and stored at −80 degrees C. until analysis.

The formulation dosed was a crystalline suspension of Compound 2 (46 milligrams of Compound 2 dosed per animal), wherein the crystalline test article was characterized with a particle size distribution of D_(v10)=12.9 μm, D_(v50)=31.5 μm, and D_(v90)=63.1 μm (as measured via laser diffraction). The formulation was prepared the day before dosing. Details of the formulation dosed are described in Table D below.

TABLE D Naltrexone Prodrug Dose Test Test Dose Level Conc. Volume Article Article (mg/kg) (mg/mL) (mL) Vehicle Storage Compound 2 186.01 250.0 0.25 0.2% ambient (free base) polysorbate 20, pH 7, 10 mM phosphate buffer

Results of the above intramuscular rat study of Compound 2 are shown in Tables E and F. In particular, Table E reports the average blood plasma levels of naltrexone in rat (n=5) over 91 days following intramuscular administration. As shown in Table E, the average blood plasma levels of naltrexone were at or above approximately 1 ng/mL over the 91 day duration. Further, Table F shows the concentrations measured for parent Compound 2, and the resultant intermediate Compound 2i for each animal. As shown in Table F, the concentrations of parent Compound 2 and the resultant intermediate were generally low to not measurable (below the limit of quantitation reported below). These data show efficient conversion of Compound 2 in rats to naltrexone over 91 days with minimal observed plasma concentrations of the intact prodrug (i.e., Compound 2) or its resultant intermediate (i.e., Compound 2i).

TABLE E Days NTX conc. (ng/mL) Standard Deviation 0.042 (1 hour) 13.82 1.7  0.33 (8 hour) 3.18 1.5 1 1.37 0.12 2 1.92 0.57 4 1.99 0.75 7 1.81 0.46 10 1.80 0.98 14 1.03 0.13 17 1.18 0.25 21 1.21 0.41 24 1.19 0.34 28 0.98 0.25 35 1.09 0.29 42 1.18 0.40 49 1.26 0.59 56 1.31 0.77 63 1.37 0.78 71 1.50 0.82 78 1.54 0.82 85 1.40 0.89 91 1.42 0.84

TABLE F Compound 2 conc. (ng/mL)* Compound 2i conc. (ng/mL)* Days Rat 1 Rat 2 Rat 3 Rat 4 Rat 5 Rat 1 Rat 2 Rat 3 Rat 4 Rat 5 0.042 (1 hr) 0.223 0.112 <0.1 0.131 0.113 <0.2 <0.2 <0.2 <0.2 <0.2  0.33 (8 hr) <0.1 <0.1 <0.1 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 2 <0.1 <0.1 <0.1 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 4 <0.1 <0.1 <0.1 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 7 <0.1 <0.1 0.175 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 10 0.111 <0.1 0.104 0.119 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 14 0.119 0.135 <0.1 0.144 0.136 <0.2 <0.2 <0.2 0.216 <0.2 17 <0.1 <0.1 <0.1 <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 21 <0.1 <0.1 <0.1 <0.1 3.25 <0.2 <0.2 <0.2 <0.2 <0.2 24 0.198 0.177 0.217 0.170 0.280 <0.2 <0.2 <0.2 <0.2 <0.2 28 0.236 0.193 0.205 0.176 0.111 <0.2 <0.2 <0.2 <0.2 <0.2 35 0.165 0.439 0.350 0.265 0.152 <0.2 <0.2 <0.2 <0.2 <0.2 42 0.155 0.156 0.212 0.199 0.205 <0.1 <0.1 <0.1 <0.1 <0.1 49 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 56 0.358 0.205 0.105 0.170 0.163 <0.1 <0.1 <0.1 <0.1 <0.1 63 <0.1 <0.1 <0.1 0.142 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 71 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 78 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 85 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 91 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 *Values with a “<” sign indicate concentrations below the limit of quantitation

Example 4: Characterization and Crystallization Method for Compound 2

Compound 2 was crystallized according to the following procedure. A 2 L reactor was set up with a 50-50 water-glycol recirculator set to 90 degrees C., preheating the jacket for 30 minutes. 1.768 grams of Compound 2 was placed into an empty 2 L reactor. To the reactor, 520 grams of isopropyl acetate was added and stirring started at 150 rpm. The solution was heated until all solids were fully solubilized. 810 grams of heptane was then added immediately as a single addition. This slurry was held at 90 degrees C. for about ten minutes, at which point the heat was turned off, and reactor and jacket were cooled without assistance to room temperature over several hours. Solids formed and were filtered by vacuum filtration.

FIG. 1 shows a powder x-ray diffraction (PXRD) pattern of the crystalline form. The PXRD pattern was collected using a Rigaku Miniflex II Desktop X-ray diffractometer, with CuKα radiation at 15 mA and 30 kV. Each sample was mounted on a zero background sample holder. A scan speed of 7.5°/min 2-theta was chosen, coupled with a sampling width of 0.2° 2-theta and a start and stop angle of 2 degrees and 40 degrees 2-theta. The crystalline form of Compound 2 can also be characterized by any one, any two, any three, any four, any five, or any six or more of the peaks in the PXRD diffractogram in FIG. 1 including, but not limited to, 7.34, 9.40, 10.80, 11.83, 12.36, 12.94, 13.77, 14.70, 15.52, 17.77, 21.16, and 23.76 degrees 2-theta (±0.2 degrees).

For example, in one embodiment, the crystalline form of Compound 2 can be characterized by the PXRD peaks at 7.34, 9.40, 10.80, and 11.83 degrees 2-theta (±0.2 degrees). In another embodiment, the crystalline form of Compound 2 can be characterized by the PXRD peaks at 10.80, 11.83, 14.70 and 17.77 degrees 2-theta (±0.2 degrees). In another embodiment, the crystalline form of Compound 2 can be characterized by the PXRD peaks at 9.40, 11.83, 12.36 and 13.77 degrees 2-theta (±0.2 degrees).

Differential scanning calorimetry (DSC) was also performed on the crystalline form of Compound 2. An endotherm was measured with an onset temperature at 209.0 degrees C. and a melt temperature at 212.4 degrees C. The DSC thermogram was measured with a TA Instruments Q2000 DSC. An approximately 3-6 mg sample was accurately weighed into a hermetic pan. Dry nitrogen was used as a purge gas (50 mL/min nitrogen) and a heating rate of 1 or 5 degrees C. min⁻¹ up to 300 degrees C. was applied.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 

1-21. (canceled)
 22. A compound of Formula Ib:

or a pharmaceutically acceptable salt thereof; wherein: both R groups, always being the same, are selected from hydrogen, halogen, unsubstituted C₁-C₄ alkyl, unsubstituted C₁-C₄ alkoxy, or unsubstituted C₁-C₄ alkylcarbonyloxy; both values of z, always being the same, are 1, 2, 3, or 4; and wherein the R groups are bound with points of attachment selected from the 1 and 1′ positions, the 3 and 3′ positions, or the 4 and 4′ positions.
 23. The compound of claim 22, wherein the R groups are bound with points of attachment at the 1 and 1′ positions.
 24. The compound of claim 22, wherein the R groups are bound with points of attachment at the 3 and 3′ positions.
 25. The compound of claim 22, wherein the R groups are bound with points of attachment at the 4 and 4′ positions.
 26. The compound of claim 22, wherein both R groups are hydrogen.
 27. The compound claim 22, wherein both R groups are halogen.
 28. The compound claim 22, wherein both R groups are unsubstituted C₁-C₄ alkyl.
 29. The compound of claim 22, wherein both R groups are methyl.
 30. The compound of claim 22, wherein both R groups are methoxy.
 31. The compound claim 22, wherein both R groups are methylcarbonyloxy.
 32. The compound of claim 22, wherein both values of z are
 1. 33. The compound of claim 22, wherein both values of z are
 2. 34-57. (canceled)
 58. A compound of claim 22 selected from the group consisting of:

and a pharmaceutically acceptable salt thereof. 59-116. (canceled)
 117. A pharmaceutical composition comprising a compound of claim 22 and a pharmaceutically acceptable carrier.
 118. The pharmaceutical composition of claim 117, wherein the composition is adapted for parenteral administration.
 119. The pharmaceutical composition of claim 118, wherein the composition provides a duration of release of naltrexone of about 9 weeks following parenteral administration.
 120. The pharmaceutical composition of claim 118, wherein the composition provides a duration of release of naltrexone of about 13 weeks following parenteral administration.
 121. The pharmaceutical composition of claim 118, wherein the parenteral administration is an intramuscular injection.
 122. A method of treating opioid dependence in a subject in need thereof, comprising administering to the subject a compound of claim
 22. 123. A method of treating alcohol dependence in a subject in need thereof, comprising administering to the subject a compound of claim
 22. 124. A method of preventing relapse to opioid dependence in a subject in need thereof, comprising administering to the subject a compound of claim
 22. 125. A method of treating alcohol use disorder in a subject in need thereof, comprising administering to the subject a compound of claim
 22. 126-133. (canceled) 